I had many problems w/ the same card but eventually
got it all working on med. quality 800x600:
1. get the 45.23 drivers
2. reset back to default clock speeds (at first)
3. set gamma to 1.5 in the game ( r_gamma 1.5 from console )
4. set AA/AF to application from the nvidia driver tab
At first I saw the same prob. as you and I think it was either
overclocking or the drivers. The other thing to watch out for
are visible artifacts/dots on the screen which are mainly caused
by overclocking but also some of the ati cards show this at default
speed. After about 10 tries I finally got the damn game to look
ok
Dave.