Epic has just made available the first patch for UT2004 addressing a number of issues and also believed to offer performance improvements.
http://www.ut2004.jolt.co.uk/
http://download.beyondunreal.com/fileworks.php/official/ut2004/ut2004-winpatch3204.exe
http://www.ut2004.jolt.co.uk/
http://download.beyondunreal.com/fileworks.php/official/ut2004/ut2004-winpatch3204.exe