choppy screen

[n3xus]

ok i need help. built a new comp. was working fine yesterday and i was able to play for a while. but now it is real choppy. it's not lag since i get the choppiness even before the login screen.

newly reformatted. installed the one download ro folder zip file provided in the links/download section. trying to avoid installing rag and sak if i can. i don't understand why it would work yesterday and not today. especially after a clean format.

computer specs:
intel core2duo 6600
2g kingston ram
nvidia geforce 8600 gts
asus p5n32-sli premium
directx9.0c

such a step up from my old 800 MHz with onboard video /swt cpu core temp is fine. not rebooting on me. am i missing something here? i play games but not the latest and greatest stuff all the time. i don't experience problems playing videos, divx or otherwise. it's just ro. but of course it would be =P anyone have suggestions?