@ Ikeoth
One of the reasons microsoft would choose not to use HD DVD as their format for an "unhackable system" is that the 360 does not play HD DVDs. The add on did, and those addons were mostly produced by Samsung. Samsung is no longer producing them, and Microsoft doesn't make HD DVD drives. They would end up in a shortage in their ability to supply people with the drives needed to play their games. Also, if they were able to put that much of a demand on their games, the drives cost would go back up (saw them for $40 at a local best buy), then they would be asking customers to reinvest in a dead format that is useful for only gaming. Sega did do that with dreamcast, and then they got out of the console business altogether. With the media integration people expect today (especially with the PS3's ability to play many formats other than blu ray such as WMV, DivX, mp4, and Xvid, ect.) some people are beginning to expect more than just games from their console. Microsoft would be setting the whole industry back a step with that kind of move, in addition to the logistics problems that supplying HD DVD drives would cause.