I had some issues with an ati card and drivers. Some of the oem cards just dont work well with updated drivers staight from ati.... You have to stick with the oem drivers and their last update.

ALso, with ati, they had a special utility to "clean all old drivers off" before doing updates. It wasnt built into the driver installer, but it's been awhile and that may have changed. I had best success when wiping clean before doing updates....