Silly question, but have you ran 3DMark05/03 again? If you have, was there a significant decrease in your score?
Have you scanned for spyware/trojan/virus possibilities? Adding to that, do you have any anti-virus apps running in the background that you didn't have before?
Have you altered any settings in Forceware control panel, specifically unser 'Global Settings'? Easily done when you're creating a profile for a specific .exe, you can accidentally enable global FSAA or whatever...
Are your CPU & RAM frequencies correct?
Are your GPU & VRAM frequencies correct? From your sig I see that you've overclocked - and this might be the answer actually - when you reinstalled Forceware did you set them to 450/1150 again? If not then that would be an obvious solution.