My friend tells me that he upgraded his hdd, and after days so he installed an oem copy of windows xp on his system. This copy of xp is already installed on one of his other systems and although he expected the system to lock up 30 or so days later - it didn't! INSTEAD it became a legal copy that is verified genuine. I asked him why he didn't install the disk that came with the system, he said that he couldn't find it. On it was his Product Key as well.