I have a Radeon X1650 Pro, and it just doesn't work - the display driver crashes trying to play any game newer than the original Unreal Tournament. I'm using the latest Catalyst drivers (7.3) but no luck. I'm trying to see if it's actually a heat issue, which I could figure out by drastically underclocking the card. However, I have no idea how to underclock something in Vista x64. Since it requires signed drivers, I can't install ATITool or the like. Any ideas?