Maybe I can trade one for some somkin' top secret fishing spots...
Well the cd key you get is tied a single PC so if a a corporation has 3000 PCs they will need 3000 keys which is a huge pain in the a$$ to manage so Microshaft sells a corporate license (HUGE dollars) so a corporation only has to track one key. If you get your hands on the "corporate key" you can install it on any PC and not have to worry about the updates.
The problem with a non corporate key is that you cannot update your PC on windws update if the key does not match the PC.
XP full is ~250$ for the full version....~250$ X xmillion copies = CHA CHING!!!