Don't take it personally. I don't like anyone.
I'd be really shocked if M$ was scanning files. I think that's sort of an invasion of privacy, and I can't imagine that they would blatently break the law. Although, it may be true that they run a checksum on the xboxdash.xbe to make sure it is legit.
I have yet to accept any theory that's been proposed yet. I know what I've seen thru my tests and nothing seems to agree with what has been stated.
BUT, Angerwound is convincingly persistant that it's possible to play live from a large HD. AND I've seen a box I modded (with a 120GB) for a friend work on Live so far. I've reflashed my eeprom with a spanking new one, and signed up with XBL under a new GT. We'll see if my box (with 250GB) is banned tomorrow.... Probably will be be.