UNITED STATES
                        SECURITIES EXCHANGE COMMISSION
                            Washington, D.C. 20549

------------------------------------------------------------------------------


                                 SCHEDULE 13G

                   Under the Securities Exchange Act of 1934
                               (Amendment No. 1)*

                     UNIVERSAL COMPRESSION HOLDINGS, INC.
                     ------------------------------------
                               (Name of Issuer)


                    Common Stock, par value $.01 per share
           ---------------------------------------------------------
                        (Title of Class of Securities)


                                   913431102
                         ---------------------------
                                (CUSIP Number)


                               December 31, 2007
                         ---------------------------
            (Date of Event which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

                               |X| Rule 13d-1(b)

                               | | Rule 13d-1(c)

                               | | Rule 13d-1(d)

* The  remainder  of this  cover  page  shall be  filled  out for a  reporting
person's  initial  filing on this form with  respect to the  subject  class of
securities,  and for any subsequent  amendment  containing  information  which
would alter the disclosures provided in a prior cover page.

The  information  required  in the  remainder  of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities  Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however,  see
the Notes).


                         Continued on following pages
                              Page 1 of 11 Pages
                            Exhibit Index: Page 10



                                 SCHEDULE 13G

CUSIP No.: 913431102                                         Page 2 of 11 Pages

................................................................................
1.     Names of Reporting Persons.

       I.R.S. Identification Nos. of above persons (entities only).


       MAGNETAR FINANCIAL LLC
................................................................................
2.     Check the Appropriate Box if a Member of a Group

       (a) [ ]

       (b) [ ]
................................................................................
3.     SEC Use Only
................................................................................
4.     Citizenship or Place of Organization

       Delaware
................................................................................
               5.    Sole Voting Power           0
Number of      ................................................................
Shares         6.    Shared Voting Power         0
Beneficially   ................................................................
Owned by Each  7.    Sole Dispositive Power      0
Reporting      ................................................................
Person With    8.    Shared Dispositive Power    0

................................................................................
9.     Aggregate Amount Beneficially Owned by Each Reporting Person

       0
................................................................................
10.    Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
       Instructions)

       [  ]
................................................................................
11.    Percent of Class Represented by Amount in Row (9)

       0% based on 30,440,190 shares outstanding as of August 2, 2007.

................................................................................
12.    Type of Reporting Person:

       IA; OO



                                 SCHEDULE 13G

CUSIP No.: 913431102                                         Page 3 of 11 Pages

................................................................................
1.     Names of Reporting Persons.

       I.R.S. Identification Nos. of above persons (entities only).


       MAGNETAR CAPITAL PARTNERS LP
................................................................................
2.     Check the Appropriate Box if a Member of a Group

       (a) [ ]

       (b) [ ]
................................................................................
3.     SEC Use Only
................................................................................
4.     Citizenship or Place of Organization

       Delaware
................................................................................
               5.    Sole Voting Power           0
Number of      ................................................................
Shares         6.    Shared Voting Power         0
Beneficially   ................................................................
Owned by Each  7.    Sole Dispositive Power      0
Reporting      ................................................................
Person With    8.    Shared Dispositive Power    0
................................................................................
9.     Aggregate Amount Beneficially Owned by Each Reporting Person

       0
................................................................................
10.    Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
       Instructions)

       [  ]
................................................................................
11.    Percent of Class Represented by Amount in Row (9)

       0% based on 30,440,190 shares outstanding as of August 2, 2007.
................................................................................
12.    Type of Reporting Person:

       HC; OO

\

                                 SCHEDULE 13G

CUSIP No.: 913431102                                         Page 4 of 11 Pages

................................................................................
1.     Names of Reporting Persons.

       I.R.S. Identification Nos. of above persons (entities only).


       SUPERNOVA MANAGEMENT LLC
................................................................................
2.     Check the Appropriate Box if a Member of a Group

       (a) [ ]

       (b) [ ]
................................................................................
3.     SEC Use Only
................................................................................
4.     Citizenship or Place of Organization

       Delaware
................................................................................
               5.    Sole Voting Power           0
Number of      ................................................................
Shares         6.    Shared Voting Power         0
Beneficially   ................................................................
Owned by Each  7.    Sole Dispositive Power      0
Reporting      ................................................................
Person With    8.    Shared Dispositive Power    0
................................................................................
9.     Aggregate Amount Beneficially Owned by Each Reporting Person

       0
................................................................................
10.    Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
       Instructions)

       [  ]
................................................................................
11.    Percent of Class Represented by Amount in Row (9)

       0% based on 30,440,190 shares outstanding as of August 2, 2007.
................................................................................
12.    Type of Reporting Person:

       HC; OO



                                 SCHEDULE 13G

CUSIP No.: 913431102                                         Page 5 of 11 Pages

................................................................................
1.     Names of Reporting Persons.

       I.R.S. Identification Nos. of above persons (entities only).


       ALEC N. LITOWITZ
................................................................................
2.     Check the Appropriate Box if a Member of a Group

       (a) [ ]

       (b) [ ]
................................................................................
3.     SEC Use Only
................................................................................
4.     Citizenship or Place of Organization

       United States of America
................................................................................
               5.    Sole Voting Power           0
Number of      ................................................................
Shares         6.    Shared Voting Power         0
Beneficially   ................................................................
Owned by Each  7.    Sole Dispositive Power      0
Reporting      ................................................................
Person With    8.    Shared Dispositive Power    0
................................................................................
9.     Aggregate Amount Beneficially Owned by Each Reporting Person

       0
................................................................................
10.    Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
       Instructions)

       [  ]
................................................................................
11.    Percent of Class Represented by Amount in Row (9)

       0% based on 30,440,190 shares outstanding as of August 2, 2007.
................................................................................
12.    Type of Reporting Person:

       HC



                                                            Page 6 of 11 Pages


Item 1(a)        Name of Issuer:

                 Universal Compression Holdings, Inc. (the "Issuer")

Item 1(b).       Address of Issuer's Principal Executive Offices:

                 4444 Brittmoore Road
                 Houston, TX 77041

Item 2(a)        Name of Person Filing:

                 This  Statement  is filed on behalf of each of the  following
persons (collectively, the "Reporting Persons"):

                 i) Magnetar Financial LLC ("Magnetar Financial");

                 ii)  Magnetar   Capital   Partners  LP   ("Magnetar   Capital
Partners");

                 iii) Supernova Management LLC ("Supernova Management"); and

                 iv) Alec N. Litowitz ("Mr. Litowitz").

                  This Statement  relates to Shares (as defined herein) held for
the accounts of Magnetar  Capital Master Fund,  Ltd, a Cayman  Islands  exempted
company  ("Magnetar  Capital Master Fund").  Magnetar Capital Partners serves as
the sole  member and parent  holding  company of  Magnetar  Financial.  Magnetar
Financial is a registered investment adviser under Section 203 of the Investment
Advisers  Act of 1940,  as  amended.  Magnetar  Financial  serves as  investment
adviser to Magnetar  Capital Master Fund. In such capacity,  Magnetar  Financial
exercises  voting and  investment  power over the Shares held for the account of
Magnetar  Capital Master Fund.  Supernova  Management is the general  partner of
Magnetar Capital Partners. The manager of Supernova Management is Mr. Litowitz.

Item 2(b)        Address of Principal Business Office or, if None, Residence:

                  The  address  of the  principal  business  office  of  each of
Magnetar Financial,  Magnetar Capital Partners,  Supernova  Management,  and Mr.
Litowitz is 1603 Orrington Avenue, 13th Floor, Evanston, Illinois 60201.

Item 2(c)        Citizenship:

                 i)  Magnetar   Financial  is  a  Delaware  limited  liability
company;

                 ii) Magnetar Capital Partners is a Delaware limited
partnership;

                 iii)  Supernova  Management is a Delaware  limited  liability
company; and

                 iv)  Mr.  Litowitz  is a  citizen  of the  United  States  of
America.

Item 2(d)        Title of Class of Securities:



                                                            Page 7 of 11 Pages

                 Common Stock, par value $.01 per share (the "Shares")

Item 2(e)        CUSIP Number:

                 913431102

Item 3.          If This Statement is Filed Pursuant to ss.ss.240.13d-1(b)
                 (or 240.13d-2(b) or c), Check Whether the Person Filing is a:

                 (a) [  ]  Broker or dealer registered under Section 15 of the
                           Exchange Act.
                 (b) [  ]  Bank as defined in Section 3(a)(6) of the Exchange
                           Act.
                 (c) [  ]  Insurance company as defined in Section 3(a)(19) of
                            the Exchange Act.
                 (d) [  ]  Investment company registered under Section 8 of the
                           Investment Company Act.
                 (e) [X]   An investment adviser in accordance with Rule
                           13d-1(b)(1)(ii)(E);
                 (f) [  ]  An employee benefit plan or endowment fund in
                           accordance with  Rule 13d-1(b)(1)(ii)(F).
                 (g) [  ]  A parent holding company or control person in
                           accordance with Rule 13d-1(b)(1)(ii)(G).
                 (h) [  ]  A savings association as defined in Section 3(b) of
                           the  Federal Deposit Insurance Act.
                 (i) [  ]  A church plan that is excluded from the definition
                           of an investment company under Section 3(c)(14) of
                           the Investment Company Act.

Item 4.           Ownership:

Item 4(a)         Amount Beneficially Owned:

                  As of December 31, 2007, each of Magnetar Financial,  Magnetar
Capital Partners,  Supernova Management and Mr. Litowitz may be deemed to be the
beneficial owner of 0 Shares.

Item 4(b)         Percent of Class:

                  The  number  of Shares of which  each of  Magnetar  Financial,
Magnetar Capital Partners,  Supernova  Management and Mr. Litowitz may be deemed
to be  the  beneficial  owner  constitutes  0% of the  total  number  of  Shares
outstanding (based upon information  provided by the Issuer in its most recently
filed registration  statement on Form 10-Q, there were approximately  30,440,190
shares  outstanding  as of  August  2,  2007.  On  August  20,  2007,  Universal
Compression  Holdings,  Inc. merged with and into Exterran Holdings,  Inc., with
Exterran Holdings, Inc. continuing as the surviving entity.)

Item 4(c)         Number of Shares of which such person has:



                                                            Page 8 of 11 Pages


Magnetar Financial:
-------------------

(i) Sole power to vote or direct the vote:                                    0

(ii) Shared power to vote or direct the vote:                                 0

(iii) Sole power to dispose or direct the                                     0
disposition of:

(iv) Shared power to dispose or direct the                                    0
disposition of:

Magnetar Capital Partners, Supernova Management, and Mr. Litowitz:
------------------------------------------------------------------

(i) Sole power to vote or direct the vote:                                    0

(ii) Shared power to vote or direct the vote:                                 0

(iii) Sole power to dispose or direct the                                     0
disposition of:

(iv) Shared power to dispose or direct the                                    0
disposition of:

Item 5.          Ownership of Five Percent or Less of a Class:

                 If this statement is being filed to report the fact that as of
                 the date  hereof  the  reporting  person  has ceased to be the
                 beneficial  owner of more  than five  percent  of the Class of
                 securities, check check the following |X|

Item 6.          Ownership  of More than  Five  Percent  on  Behalf of  Another
                 Person:

                 This Item 6 is not applicable.

Item 7.          Identification  and  Classification  of the  Subsidiary  Which
                 Acquired the Security  Being Reported on By the Parent Holding
                 Company:

                 See disclosure in Item 2 hereof.

Item 8.          Identification and Classification of Members of the Group:

                 This Item 8 is not applicable.

Item 9.          Notice of Dissolution of Group:

                 This Item 9 is not applicable.

Item 10.         Certification:

                 By signing  below  each of the  Reporting  Persons  certifies
that, to the best of their  knowledge and belief,  the securities  referred to
above were not acquired and are not held for the purpose of or with the effect
of changing or  influencing  the control of the issuer of the  securities  and
were not acquired and are not held in connection  with or as a participant  in
any transaction having that purpose or effect.



                                                            Page 9 of 11 Pages


                                   SIGNATURE

      After reasonable inquiry and to the best of my knowledge and belief, the
undersigned  certify that the information set forth in this statement is true,
complete and correct.

Date: February 12, 2008              MAGNETAR FINANCIAL LLC

                                     By:    Magnetar Capital Partners LP
                                            As Sole Member

                                     By:  /s/ Alec N. Litowitz
                                          -----------------------------
                                     Name:  Alec N. Litowitz
                                     Title: Manager  of  Supernova  Management
                                            LLC,   as   General   Partner   of
                                            Magnetar Capital Partners LP

Date: February 12, 2008              MAGNETAR CAPITAL PARTNERS LP


                                     By:  /s/ Alec N. Litowitz
                                          -----------------------------
                                     Name:  Alec N. Litowitz
                                     Title: Manager  of  Supernova  Management
                                            LLC,   as   General   Partner   of
                                            Magnetar Capital Partners LP

Date: February 12, 2008              SUPERNOVA MANAGEMENT LLC


                                     By:  /s/ Alec N. Litowitz
                                          ------------------------------
                                     Name:    Alec N. Litowitz
                                     Title:   Manager

Date: February 12, 2008              ALEC N. LITOWITZ


                                     /s/ Alec N. Litowitz
                                     ------------------------------



                                                           Page 10 of 11 Pages



                                 EXHIBIT INDEX


Ex.                                                                     Page No.

A.    Joint Filing  Agreement,  dated February 12, 2008 by and among
      Magnetar   Financial  LLC,   Magnetar   Capital  Partners  LP,
      Supernova Management LLC, and Alec N. Litowitz ........................11




                                                           Page 11 of 11 Pages


                                   EXHIBIT A

                            JOINT FILING AGREEMENT

      The  undersigned  hereby  agree that the  statement on Schedule 13G with
respect to the Common Stock of Universal Compression  Holdings,  Inc. dated as
of February 12, 2008 is, and any amendments thereto  (including  amendments on
Schedule 13D) signed by each of the  undersigned  shall be, filed on behalf of
each of us pursuant to and in accordance  with the provisions of Rule 13d-1(k)
under the Securities Exchange Act of 1934, as amended.


Date: February 12, 2008              MAGNETAR FINANCIAL LLC

                                     By: Magnetar Capital Partners LP
                                            As Sole Member

                                     By:  /s/ Alec N. Litowitz
                                          -----------------------------
                                     Name:  Alec N. Litowitz
                                     Title: Manager  of  Supernova  Management
                                            LLC,   as   General   Partner   of
                                            Magnetar Capital Partners LP

Date: February 12, 2008              MAGNETAR CAPITAL PARTNERS LP


                                     By:  /s/ Alec N. Litowitz
                                          -----------------------------
                                     Name:  Alec N. Litowitz
                                     Title: Manager  of  Supernova  Management
                                            LLC,   as   General   Partner   of
                                            Magnetar Capital Partners LP

Date: February 12, 2008              SUPERNOVA MANAGEMENT LLC


                                     By:  /s/ Alec N. Litowitz
                                          ------------------------------
                                     Name:   Alec N. Litowitz
                                     Title:  Manager

Date: February 12, 2008              ALEC N. LITOWITZ


                                     /s/ Alec N. Litowitz
                                     ------------------------------