Tried this (Kill Bill 1080p sample) on my C2D MacBook Pro (2.16) and it played flawlessly. 50% CPU usage and smooth playback. Quicktime however, wouldn't even open it. Disgusting scene btw...funny but disgusting.
For some reason seeing it in HD really upped the intensity in that scene, when I watched it on dvd it wasn't nearly as gruesome. Maybe this HD thing is for real