There is some misinformation from the other 'answerers' which I should address. A flashed Xbox 360 does not have a reprogrammed BIOS (that would require some serious hacking skill into the Xbox 360's boot sectors) but a disc drive who's firmware/software is replaced with a modified or 'cracked' version to trick the Xbox 360 into 'thinking' that burnt copies of games are the real deal. Many flashed Xbox 360's can be detected on Xbox Live, and MS is cracking down on them. It isn't really worth buying if you can't go on Xbox Live. If you do get detected your Xbox 360 is permanently banned, and therefore unusable online so only SP parts of games will be available to play.
