Reinstalling XP

I have what Micro$oft considers to be an illegal copy of XP Pro. I just received a new copy (with a different key) from our Corporate office. I want to reload XP Pro to make it a valid copy but don’t want to have to reinstall all of my other programs.

When I try to do the load into the same folder as the original installation, it prompts me that all of my user info and programs will be lost. This is unlike Win2K that would allow you to reload into the same folder and not lose your registry settings.

Is there a way to do a reload without losing everything? Is this simply a matter of getting the existing XP software to recognize a different key?