What I've taken to doing is looking card up on techpowerup.com - say, like a GeForce 9800 GTX+. They're pretty good at listing the final release drivers for a particular card/OS. In this case, 340.52 for Windows XP. I don't take what they say as gospel, but I find it a good place to start. I also search out reviews from when the card was released and see what drivers they were using at the time on their test systems - for a 9800 GTX+ looks to be about 177.xxx. So that gives me a range of drivers to play around with and I just try a few till I arrive on one that suits my needs.