>>> Sure, you could install XP onto the new machine, use the CD key and then activate using Vista's key. But, then you would have no OS on your Nov. machine. Boy, this was much easier when you just had one license and one machine.
Actually, happily, that's not true. After 4 months, Windows XP activation will go back to "unactivated" mode... so you can set up the Windows XP on a new computer (or transfer over the clone)even though your old computer still has Windows XP on it.
Now, the Microsoft expects to get paid for all installations, so the EULA states that only 1 license per machine, but if you are going to use the old one temporarily to get to your old files while installing the new computer, I'm sure that it's OK.
Al