Re: machine with null serial number?

FROM : John Joyce
DATE : Sat Mar 29 18:03:07 2008

Indeed, on repair, the computer should have the old serial number. 
This is why it is also located on the case, exact location depends on 
the model. The only time there should ever be a new serial number is 
when a Mac is outright replaced. Definitely, it is a bad idea to 
depend on the serial number at all for software. MAC addresses are 
not entirely difficult to spoof either. The best case is to either 
have users register the product, the Microsoft way, or simply accept 
that a certain level of piracy is inevitable with desirable software.