It's funny because I'm on Nvidia's site right now. There are no specific VIsta drivers for the 8800 series video cards, but all the previous chipsets do. Hmmm. I'm sure it will work great regardless of that. It's a powerful card and you probably don't even need drivers from nvidia to run it. Just use Windows settings, crank up the resolution and everything should be smooth. I would also try the XP Pro 64 bit drivers too, to see how that works out.
I also heard that for 64 bit version of Vista, getting 2GB is better than having 1GB as far as performance goes. Got that info off of PC World magazine.