I have installed an XP CD on one computer, then now, about 3-4 years later, i installed the same disk with same Key onto my Laptop, but it wants me to activate it, i can log on now, and then i called microsoft and entered my product ID, then it said, this has already been installed on another PC, and wont tell me, is there anyhting i can do so i can use Windows xp on another PC, without having to buy a new XP Pack??