HD video playback - VC-1
Unlike Babel, Peter Jackson's version of King Kong is encoded in the VC-1 format that's more prevalent among HD DVD movies right now. This disc is encoded at a more leisurely ~17 Mbps.

This one is a clear win for the GeForce 8800 cards on CPU utilization. The 2900 XT 1GB GDDR4 again draws the least power of the bunch during playback, though.