I just got UT2k3 for $19.95 at my local software shop.
I applied the latest update and the performance is pretty good.
In the UT2003.ini file, I changed:
CacheSizeMegs to 64
VARSize to 64
ForceCompression to true
bCapFramerate to false
UseTripleBuffering to True
Within the game, in the details menu, I changed all the detail level to the lowest possible (Is this necessary?) and I'm using the 1024x768 resolution.
Does anyone have tips on how the tweak UT2k3 for greater performance?