|Vendors should Activate the computer. Then the buyer can register if they want to. |
I've never registered any computer or software, but you do what you want.
They may have installed using a mufti license cd or used different keys to install and never updated it to be the same as the sticker on you computer.
SIW , Magic Jelly bean...both free can find the keys on your system that were used to install and activate. Microsoft has a free key updater. If your xp is legal it will change (update ) the keys to correspond with those on the COA sticker.