ATI Technologies have released version 4.9 of their Catalyst video card drivers. In the release notes, it is stated that these new drivers could offer up to a 25 percent increase in performance in UT2004:
If you own a Radeon series video card, you can grab these new drivers from their drivers page.UT2004 performance improves considerably on the ATI RADEON™ 9500 PRO, RADEON™ 9700 PRO RADEON™ 9800 PRO and RADEON™ 9800 XT products. The benefit can be 25% or more in some circumstances, particularly at extreme graphics settings such as 6xAA + 16xAF.