When you install Windows XP Pro, I believe you set up a root account and a regular, admin account. If you boot into safe mode you should be able to log in to the original admin account (if you set a password, you would need to know that).
There are also some tools that can overwrite your current password. Check out this article. In addition, TechTV ran a great feature on password recovery. You can find the links here.
My, that must really suck. Well, your best bet would be to, actually, hmm... Have you tried googling the subject? I don't think that there would be any way around it. Maybe RBS would know.