I also have a XFX GeForce 7900 GS, and an OEM version of Home Premium, so we're basically in the same boat. I used to get blue screens all the time. I did a clean reinstall of Vista, and everything was cool for months. Now they're back. I don't have the problem when I open pictures (but then again I spend most of my time browsing the Internet and watching videos). There was one time, though, when I was viewing a slideshow and got a blue screen. That was the first of the new waves of blue screens for me.
The problem is probably not with the graphics card; The driver included should work fine. I'm considering buying a Registry Cleaner to see if I can get rid of my blue screens. Let me know when you fix your problem.