Remeber that running linux on the first xbox was made possible by exploiting a weakness in the savegame structure of some 007 game (an in deed other games/dashboard later). So the first booting of linux we saw was actually made though the game. Loading a savegame, which in turn crashed and made allowed the unsigned code to be run.

I'm not sure this is the case with the 360, but the first xbox had a security system that prevented code to be called unless it was from a "safe" caller, in what is called the chain of trust. One trusted component calls the other (instanciated by the firmware). The trick is, in other words to trick something into calling unsafe code. For instance by exploting bugs in games, such as illustrated above.

Whats the point in upscaling the crappy dvd resolution to 1080p??? Buy yourselfs a cheap media center with som good hardware..it will serve the same purpose (if you need it) and more. You can even upgrade it to an hd-dvd (afterall, existing hd-dvd players are ordinary x86 computers)