I'm running a GF 5600Ultra 256mb card with 71.89 drivers which work well. Haven't tried the newer ones yet.... chicken because I've had no problems so far.
Go here to find the older cards mixed in with the newst ones....
http://www.pricewatch.com/video%5Fcards/ and look in Cards- Video section here:
http://www.pricewatch.com/video%5Fcards/. Check often as there are some good, and different, deals every day.