based on your original description of the banning, they must be banning the account and the xbox, but no longer banning the xbox by MAC address...since we all know that gets replaced with a new eeprom. how could they ban the box itself without using the MAC address? does a new eeprom change the box's serial number? it's a little strange to me that ever used MAC address and not the serial number to begin with...anyways, the ban must be based on a value stored in hardware somewhere or stored in a file on the hdd...or perhaps it's based on the hdd itself (i.e. non-stock hdd = banned)...very interesting...
the M$ war on xbox terrorism has begun!