Messed up Display

System:

Dell XPS 620i
Intel Quad core
8 gigs ram
9800 gt
1600x1050 ( i think )

I upgraded to windows 7 (64 bit) from Vista (64 bit). Install went smooth, no error windows or anything. Then I started World of warcraft, and my screen froze. The screen got a fuzzy with with distorted color pixels everywhere and stuff. So I did a hard reboot, but the fuzzy, colorful screen still appeared a soon as the Dell logo came on. the log in screen was the same and big. Looks like resolutuon was at 640x480 or smaller with the distorted pixels. I went to my display options but my nvidia control panel was gone. I could not change display setting either. I reinstall my old graphic drivers, it seemed to work, but 1 minute or so in it did the same thing. But when i hit reboot i got prompted to do a system restore. I did. It worked fine for a minute after i logged in and did the same thing. Using the distorted display resolution, i installed old drivers, new drivers, beta drivers for my 9800 but it did the same thing, display goes back to normal after a reboot, then distorts/freezes after a minute or so. I suspect It is hardware failure with my 9800 graphic card. But before i buy a new one, is there anything else that might be causing the problem? Should i reinstall Winows 7? or go back to Vista?

I don't know of a way to diagnose the problem 100% concisely, but it is either the video card or the driver installation, not the OS. When you updated the driver, did you use Driver Sweeper in Safe Mode to remove the old driver first? Did you get the driver update directly from Nvidia or Windows Update? If you did install the latest Nvidia driver in Safe Mode after using Driver Sweeper, I would tend to believe that the card itself is the problem.

No i didn't do a driver sweep. But when i did the system restore, It wiped everything. So I reinstalled nvidia drivers and still the same problem.