Start here:
http://www.tlc.state.tx.us/research/redist/redist.htmClick on the REDVIEWER, and pick the "U.S. Congressional Districts in Effect for the 2004 Elections". It could take a while to load, depending on your connection...
PLANC01374 is the one you want.
Did I mention it could take a while to load? If it's working...at this moment it appears not to be. In any event, there is voting preference data - "a weighted average of the results of all general election statewide contested contests" from 2000 - available, either through REDVIEWER or through the report package pdf here:
http://www.tlc.state.tx.us/research/redist/redist.htm