Well I have called all companies through their 1-800 numbers. A Microsoft Represenative stated they use HD-DVD discs. Although, I may be wrong. But however, Wii is compatible with DVD-Roms, but cannot play DVD movies, because of the way it was programmed. So even if the XBOX did [or does] they programmed it differently. I'm assuming they sold a seperate drive to accommodate everyone with a DVD player upgrade without making a built-in HD-DVD console upgrade (Market Strategy).