I recently upgraded my trusty NVIDIA Ti4400 card to the 6800GS by eVGA. Since the necessary power supply upgrade (went with Enermax again) I've enjoyed amazing graphics performance on my over 3-year-old system. My only concern is that the 6800 runs at 60C, and over 70C while running WoW.
Today I ordered the Arctic Cooling NVsilencer:
I'll let you know how it goes, but from what I've read, it should knock 10-20C off both the idle and the working temperature.