Register a free account to unlock additional features at BleepingComputer.com
Welcome to BleepingComputer, a free community where people like yourself come together to discuss and learn how to use their computers. Using the site is easy and fun. As a guest, you can browse and view the various discussions in the forums, but can not create a new topic or reply to an existing one unless you are logged in. Other benefits of registering an account are subscribing to topics and forums, creating a blog, and having no ads shown anywhere on the site.
Well, as far as I know, there is no way to change who it's registered to, unless you completely wipe the harddrive and reinstall XP fresh, but you can change the name the basic windows account is under.
you should be able to use this article to change who your computer is registered too, warning, this requires editing the registry, which should not be done unless your confident you know what your doing.