Is wal-mart going to be selling the discs in stores or just the players? if they are selling HD-DVD movies aswell than this could mean trouble for blu-ray. I'm not about this(not owning a player for either formats I haven't actually cared to check)but i heard that most retailers don't want to sell either format, if that's true then getting on store shelves of a store like wal-mart could give HD-DVD a significant boost. Whether or not it will kill blu-ray depends on how many people own hdtv's when this all happens, and the price of the players in question.
! think the one problem with the format war is that it is all very dependant on how many people own hdtv's, so even though blu-ray is winning it is only selling well in comparison to hd-dvd.
