i'm impressed to hear, that it's possible to use an AppleTV-image to run it on an intel-mac!
the Problem: i have 2 ppc g4 mac's and an hackintosh
but for now: there is a skin in development for xbmc on xbox, called xTV
a good tutorial is located here: click
looks good: video
i have tested it and i can say: GREAT! but it's clear, that HD is not possible on xbox, but who cares...i don't have a HD-TV
Mikemad