zaba_3,if you are really into RTS's (and I mean, you really love them), I very strongly recommend Starcraft and its expansion set, Brood War. They are both incredible RTSes and they have insanely low system requirements too (and they both run perfect under XP).
Also, if you are into FPSes, Soldier of Fortune is a pretty cool (if not exceedingly violent) game which should run fine on your card (not 100% sure about the sequel).