I recently had to replace my CPU with a new one. When the system started up it gave a me a "You need to activate windows XP" message. I have never activated windows (It was done at the store). Can someone tell me what to do to re-activate windows? I have no clue what to do, since I've never seen this before. I have a LEGIT copy of Windows XP that came with the system. Scott P.S. Please hurry, I only have three days to do this.