Exhibit 4.1


AMENDMENT TO RIGHTS
AGREEMENT


This Amendment to the Rights Agreement between Pogo
Producing Company, a Delaware corporation (the “Company”), and
Computershare Trust Company, N.A., as Rights Agent (the “Rights Agent”),
dated April 26, 1994, as amended (the “Rights Agreement”), is hereby
adopted as of July 17, 2007.


WHEREAS, the Company has entered
into the Rights Agreement, as heretofore amended, specifying the terms of the
Rights (as defined in the Rights Agreement);


WHEREAS, Section 27 of the
Rights Agreement permits the Company in its sole and absolute discretion to
amend the Rights Agreement prior to any Distribution Date (as defined in the
Rights Agreement);


WHEREAS, no Distribution Date
has occurred;


WHEREAS, the Company desires to
amend the Rights Agreement in accordance with Section 27 of the Rights
Agreement;


WHEREAS, the Company proposes to
enter into an Agreement and Plan of Merger, dated as of July 17, 2007 (the
“Merger Agreement”), by and among Plains Exploration & Production
Company, a Delaware corporation (“Parent”), PXP Acquisition LLC, a
Delaware limited liability company and a wholly owned subsidiary of Parent (“Merger
Sub”), and the Company;


WHEREAS, the Board of Directors
of the Company has determined it advisable and in the best interest of its
stockholders to amend the Rights Agreement to enable the Company to enter into
the Merger Agreement and consummate the transactions contemplated thereby
without causing Parent or any of its subsidiaries to become an “Acquiring
Person” (as defined in the Rights Agreement).


NOW, THEREFORE, in consideration
of the premises and mutual agreements set forth herein and in the Rights
Agreement, the parties hereby agree as follows:


SECTION
1.   DEFINITIONS. Capitalized terms used and not
otherwise defined herein shall have the meaning assigned to such terms in the
Rights Agreement.


SECTION
2.   AMENDMENTS TO RIGHTS AGREEMENT. The Rights Agreement
is hereby amended as set forth in this Section 2.


(a)           The definition of “Acquiring Person”
in Section 1 of the Rights Agreement is amended to add the following sentence
at the end thereof:


“Notwithstanding anything in this Agreement to the
contrary, none of Parent or Merger Sub or any Subsidiary, Affiliate or
Associate of either of 













them shall be deemed to be an Acquiring Person, either
individually or collectively, as a result of any or all of the Merger Events.”


(b)           The definition of “Distribution Date”
in Section 1 of the Rights Agreement is amended to add the following
sentence at the end thereof:


“Notwithstanding anything in this Agreement to the
contrary, a Distribution Date shall not be deemed to have occurred as the
result of any or all of the Merger Events.”


(c)           The definition of “Flip-In Event” in
Section 1 of the Rights Agreement is amended to add the following sentence
at the end thereof:


“Notwithstanding anything in this Agreement to the
contrary, none of the Merger Events shall be a Flip-In Event.”


(d)           The definition of “Flip-Over Event”
in Section 1 of the Rights Agreement is amended to add the following
sentence at the end thereof:


“Notwithstanding anything in this Agreement to the
contrary, none of the Merger Events shall be a Flip-Over Event.”


(e)           The definition of “Stock Acquisition
Date” in Section 1 of the Rights Agreement is amended to add the following
sentence at the end thereof:


“Notwithstanding anything in this Agreement to the
contrary, a Stock Acquisition Date shall not be deemed to have occurred as the
result of any or all of the Merger Events.”


(f)            The definition of “Expiration Date”
in Section 1 of the Rights Agreement is amended to replace the words “and
(iv)” with “, (iv)” and to add at the end thereof the words “and (v) the
Effective Time (as such term is defined in the Merger Agreement) of the Merger
(as such term is defined in the Merger Agreement).  The Company hereby agrees to promptly notify
the Rights Agent, in writing, upon the occurrence of the Effective Time, which
notice shall specify (i) that the Effective Time has occurred, and (ii) the
date upon which the Rights established hereby expired and this Agreement
terminated.”


(g)           The following definitions shall be
added to Section 1 of the Rights Agreement:


“ “Merger Agreement” shall mean the Agreement and Plan
of Merger dated as of July 17, 2007 by and among Parent, Merger Sub and
the Company.”


“ “Merger Events” shall mean (i) the announcement
of the Merger (as such term is defined in the Merger Agreement), (ii) the
execution and delivery of the Merger Agreement, 
(iii) the conversion of Common Stock 



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into the right to receive the Merger Consideration (as
such term is defined in the Merger Agreement) in accordance with Article I
of the Merger Agreement or (iv) the consummation of the Merger or any
other transaction contemplated by the Merger Agreement.”


“ “Merger Sub” shall mean PXP Acquisition LLC, a
Delaware limited liability company and a wholly owned subsidiary of Parent.”


“ “Parent” shall mean Plains Exploration &
Production Company, a Delaware corporation.”


SECTION 3.           MISCELLANEOUS.


(a)           The term “Agreement” as used in the
Rights Agreement shall be deemed to refer to the Rights Agreement as amended
hereby.


(b)           The foregoing amendment shall be
effective as of the date first above written, and, except as set forth herein,
the Rights Agreement shall remain in full force and effect and shall be
otherwise unaffected hereby.


(c)           This Amendment may be executed in two
or more counterparts, each of which shall be deemed to be an original, but all
for which together shall constitute one and the same instrument.


(d)           This Amendment shall be deemed to be
a contract made under the laws of the State of Delaware and for all purposes
shall be governed by and construed in accordance with the laws of such State
applicable to contracts to be made and performed entirely within such State; provided, however, that all provisions
regarding the rights, duties and obligations of the Rights Agent shall be
governed by and construed in accordance with the laws of the State of New York
applicable to contracts made and to be performed entirely within such State.



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IN WITNESS
WHEREOF, the parties hereto have caused this Amendment to be duly executed as
of the day and year first above written.


	
  

  	
  POGO PRODUCING COMPANY

  
	
   

  	
   

  	
   

  
	
   

  	
  By:

  	
  /s/ John O. McCoy, Jr.

  
	
   

  	
   

  	
  Name:

  	
  John O. McCoy, Jr.

  
	
   

  	
   

  	
  Title:

  	
  Executive Vice President and Chief Administrative
  Officer

  
	
   

  	
   

  	
   

  
	
   

  	
  COMPUTERSHARE TRUST COMPANY, N.A.

  
	
   

  	
   

  
	
   

  	
  By:

  	
  /s/ Mark Asbury

  
	
   

  	
   

  	
  Name:

  	
  Mark Asbury

  
	
   

  	
   

  	
  Title:

  	
  Relationship Manager

  
					



 



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