[Solved] Upgraded GPU, All games crash!

Current Build:
Gigabyte DS3L-P35
Earthwatts 80Plus 500W PSU
Core2 Quad Q6700
4GB DDR2 FSB 1066
160GB SATA2 & 250GB SATA2 HDDS
24" Dell 2407W LCD 1920x1200
Windows XP 32 bit

I just replaced my Nvidia 7900GS 256MB with a Gigabyte ATI Radeon 4670 1GB. Every game locks up as soon as I get to actual gameplay. So far, I have tested...

Age of the Empires III
TrackMania Nations Forever
Sid Meier's Pirates

They all crash within 30 seconds. I can't even get to the AoE III gamescreen. As soon I go into video options it crashes.

What I did:

1. Removed Nvida control panel & driver (forgot to remove Purevideo and Nvidia MCE addins).
2. Swapped GPU cards
3. Booted and loaded ATI drivers (Cataylst 9.9)
4. Games all crash
5. Removed Purevideo & MCE addins
6. Games still crash
7. Ran DirectX 9.0C August 2009 update (not sure how old my DX updates were)
8. Reinstalled Catalyst 9.9 (haven't tested games yet...at work)

Does anyone have any suggestions on things to check? I'll update when I get home to see if the DX update and driver reinstall made a difference.

I would reinstall, except it would be a ROYAL pain, as gaming is just a secondary item on this OS...I have a TON of software that I use regularly. In fact, when I built this machine, the hard drive was pulled from my old Dell XPS 400 and I didn't reinstall then...just ran an OS restore to get around the activation key issue so I wouldn't have to reconfigure everything.

Maybe it's time to bite the bullet and reinstall. But I'm not sure how that will work since I'm dual booting Win 7 RC. I thought you had to install the OS in a specific order for the dual boot to work properly.

Can anyone recommend a driver sweep program?

I suppose I could just install the games in Windows 7, as that is a farily clean install. It had the Nvidia drivers, but Windows 7 seems to handle drivers better. I'll look into Driver cleaner pro.

Oops.

Earthwatts 80Plus 500W