OK, I now know I want to be able to play 720p HD clips on the cube if possible, since my LCD doesn't have the res to go any higher.
Apple recommends a 1.8 G5 or 1.83 Core Duo with 256MB RAM and 64MB graphics card as the minimum. For 1080p, they recommend dual 2 G5 or 2.0 Core Duo which make me wonder if clock speed is the most important factor here.
Are these requirements drawn up with Apple models in mind rather than upgraded Macs? Does system RAM make much difference with video playback? How about GPU?
Will 1080p scale back to 720p if there aren't enough pixels available? Which system requirements would apply under such conditions?
Am I really going to need a 1.8GHz (G4) upgrade to get close to playing back 720p?

Opinions PLEASE!!!!!!