I had the same prob with my GF2- I dunno if you're experiencing it, but when I loaded my drievers in Windows it froze after splash screen. I disabled my AGP 4x and the problems went away. First and foremost, I'd definitely try disabling 4x via the BIOS. For my system, it wasn't an option, so I was left with solving it the hard way. What I did, and I'm not saying it will work for you, was use a little tape and tape the last pin on my AGP card, the one furthest from the metal panel cover. I used scotch tape, though I've heard electrical tape is better. I covered both sides of the very last pin and when I booted up, no problems.
Good luck!
You're not that stupid, I'm just that smart.