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. It's also encoded at a more leisurely ~17 Mbps. The change in formats is notable because the bitstream processor in Nvidia's VP2 unit can't fully accelerate VC-1 decoding, while ATI's UVD can. Nvidia downplays this difference by arguing that VC-1 is less difficult to decode anyhow, so the additional hardware assist isn't necessary. Let's see what kind of difference we're talking about.

The Radeon HDs do indeed have an advantage over the GeForces in VC-1 playback, but it only amounts to about 5% less CPU utilization. Of course, that's with a relatively fast 2.93GHz dual-core processor, and these cards will probably find their way into systems with slower CPUs, where the reduction in CPU load will be relatively larger. (Then again, with the way CPU prices have been going, I'm not so sure about that. If Intel follows through with its rumored quad-core price drop, the picture will change quite a bit.)

The Radeons' more frugal use of CPU cycles with this VC-1 disc doesn't really translate into a power advantage. The 2600 XT still draws over 10W more than the 8600 GT.