Watson
Said..
If you want very good performance. I would recommend at least a 320 MB 8800 GTS.
Get an 8800 NVIDIA ultra... you may need a bigger power supply ... after that if u want more your going to need a new motherboard that supports sli ... 4 gigs of ram isn’t going to work unless u know how to get windows to detect it ... I wouldn’t go more than 3 really it will be enough .. 2 would probably actually be fine with XP and wouldn’t hold u back...