|Yes, you can run a 32-bit OS on a 64-bit computer.|
No, you can't clone your existing 32-bit OS. As explained above, it probably won't run. If it did run it would need to be reactivated with a retail key (an OEM key wouldn't work because of the change of hardware). If you have a retail key you should have (or can easily get) an install CD. Install the XP from scratch.