Video Performance Problem

I have a dual 2.7ghz G5 with a GeForce 6800 Ultra, both of which I've had for a while now. I don't play any video card-intensive games, so I don't know if it's an all around video card problem or just a Quartz problem, but things like the little pop open animation when you open a folder, or dragging a folder around have been choppy for the last week or so. Anyone have any suggestions?

(Yes, I have rebooted, and I have repaired permissions, and I have also used compressed air to get the dust out of the video card's fan)