                                POWER OF ATTORNEY

     Know all by these  presents,  that the undersigned  hereby  constitutes and
appoints  each of Joan  Hague and Javier  Solis,  signing  singly,  his true and
lawful attorney-in-fact to:

     (1)  execute  for and on behalf of the  undersigned  Forms 3, 4 or 5 and in
accordance  with Section  16(a) of the  Securities  Exchange Act of 1934 and the
rules thereunder;

     (2) do and  perform  any and all acts for and on behalf of the  undersigned
which may be necessary  or desirable to complete the  execution of any such Form
3, 4 or 5 and the timely filing of such form with the United  States  Securities
and Exchange Commission and any other authority; and

     (3) take any other action of any type  whatsoever  in  connection  with the
foregoing which, in the opinion of such attorney-in-fact,  may be of benefit to,
in the best  interest  of, or legally  required  by, the  undersigned,  it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned  pursuant to this Power of Attorney  shall be in such form and shall
contain such terms and  conditions as such  attorney-in-fact  may approve in his
discretion.

     The undersigned hereby grants to each such  attorney-in-fact full power and
authority  to do and perform all and every act and thing  whatsoever  requisite,
necessary  and proper to be done in the exercise of any of the rights and powers
herein  granted,  as fully to all intents and purposes as such  attorney-in-fact
might or could do if  personally  present,  with full power of  substitution  or
revocation,  hereby ratifying and confirming all that such attorney-in-fact,  or
his substitute or  substitutes,  shall lawfully do or cause to be done by virtue
of this  power of  attorney  and the  rights  and  powers  herein  granted.  The
undersigned  acknowledges  that the foregoing  attorneys-in-fact,  in serving in
such  capacity at the request of the  undersigned,  are not  assuming any of the
undersigned's  responsibilities  to comply  with  Section  16 of the  Securities
Exchange Act of 1934.

Unless rescinded earlier in writing,  this Power of Attorney will expire on July
1, 2008.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 1st day of July 2003.

                                    Signature:   /s/David Davenport
                                                 -------------------
                                                 David Davenport

