So, I have two dinosaur Dell desktops. One is a Dimension 3000 and the other an 8400. I only have the Windows XP disc for the 3000 one and I am wondering if I could reformat the hard drive on the 8400 and reinstall XP using the disc. Would everything be okay, provided I back up the necessary driver files on a flash drive? I have the CD key or product key (whatever it's called). Would any other kind of alphanumeric number be needed?