I have 3 computers here at home 1 64 bit Vista (newer laptop), and fairly beefy XP desktop, then my older but not too outdated laptop running XP. It is this 3rd laptop here that I'm worried about upgrading. I want to do clean installs on all 3 machines. I'm worried about what to do or what the install will be expecting during the installation of the older laptop? Does it want me to type in a Product ID, insert a XP CD, or ??? Can I use a product ID from the other XP OS (as a workaround?). I can't find the sticker or anything anywhere for this one?