Weeeel, to get better performance, i'd suggest buying a better card.
But, before you do that, there are a few things that you can do to speed up your whole PC as well as performance applications, such as UT2K3.
1.Get Ad-aware and run it, clean all the spyware and adware from your PC.
2. Defragment your hard drive, will definately improve performance, unless done recently.
I'm sure there are some more tips that our veteran forum members can give you.
Ad-aware link:
http://download.com.com/3000-2094-10...ml?legacy=cnet