Well omega drivers are 3rd party, open source drivers. They have them for ATI, Nvidia, and any other card out there.
GET EM HEREThey're the best drivers out there. Most of the time they're better than the company's own. And you never know, maybe the guys who make them know about the OGL problem, and fixed it?
Just back up your oldies before you get them. In-case it makes matters worse (I doubt they will) Just some words of caution.
EDIT -
Oh damnit. Upon further research, i guess the guy who writes the drivers had a bit of a problem. His wife had a.. problem, and he hasnt been working on anything really. So as of now, there are no ATI drivers for Vista. But the site says they'll be in soon.