Ditch, when you install XP you will, at some time, be asked for a long number that will look something like 'k7067f g704g4 kj4ty6 ewr6jf' (yep, 24 digits). Thats what I mean by 'registration number' but it could of course be a 'product key'. Whatever, you'll need that early on in the installation process. Once you've installed XP you then have so many days (I think its 20) to register (I think Microsoft call it 'validate) the copy on-line. This is an automatic process once you've set up your internet access. If you don't validate your installation then XP will stop running on the PC. However,