How do you go about re-installing XP on the same machine that its currently
on, without Microsoft questioning the copyright. I know I would have to
register it again also using the same product key codes.
First of all, there is no copyright issue.
Second, there is no registration required. Registration is completely
optional, and used only for Microsoft's marketing purposes.
What is required is *activation*.
Activation is completely normal, and the fact that it was already done
on that machine is irrelevant. Just go about activation normally after
you reinstall Windows. You will either be permitted to activate
normally over the internet, or give an 800 number to make a voice call
to. Either way is quick is easy.