at your speed, dont bother for the 9100 or the 9000. Maybe go for a geforce 4 mx420. Reason is, I used to have a 533mhz amd processor, and a gf2mx400.
Anyways I tried to run renegade on it, it meets the requirements, and ran about 10 - 15 frames/s. I got a new 1800+ athlon xop system, and runs well over 80fps on same settings. So what im trying to say is, your cpu is starving your card. The only reason i said mx420 is cause they dont selll geforce2's to my knoledge anymore. Get a geforce 4 mx, or a geforce 2 mx if you can find one, no matter what card you get, you wont have better performance then a gf2 mx.
So IMO, oyu should get a new comp, but for video, get a cheap gf4 mx420 pci. The best pci is way out of your league.