INTELCRAZY
banned
I just installed drivers and was playing Plasma Pong, I used to get 120FPS on my X1300PRO, now only 60FPS with the 8800GTX. 
FORCE turn off vertical sync in the nvidia control panel.
Go to the nvidia control panel, manage 3D settings, and force off vertical sync.
Vertical sync forces your monitor to render only as many images as you refresh rate allows, to prevent the screen from tearing. The thing is, if your monitor has a refresh rate of say 60hrtz, that's basically a cap-off of your FPS. Whether Vertical sync is on or not, you'll will never see more than 60FPS because of the nature of todays LCD monitor.
Many people still believe that when FRAPS says your card is rendering 100fps, that's what they're seeing, but it's not true for the reasons stated above.
My monitor can go to 75Hz.... So, do I still need to do this?
If you have it set on 75hertz, then no. Vertical sync would cut you off at 75fps. And this wouldn't be a solution because you said you were hitting 60fps tops. If all you're saying is that your monitor can achieve a 75hert refresh rate then it is a solution.
Also have you done as suggested? tried an actual game?