Insult to Injury, Not a good year

[dragonlord]

The M.A.C. Address is unique to each computer (specifically the network adapter), however it is only ever used on the local network, also a most computers now come with an identity chip that can be used to uniquely identify the computer, though it's easier to just take a permant marker to the motherboard and case (or buy an etching kit for the case if you want something they can't just sand off)