If the version of windows came with your PC all you have to do iss call them. Try to activate it when it gives you that toll free number call it. It is about a 5-10 minute call. Give them your situation and they will give you a new activation ID. That way you dont have to do any kind of work around.
It isnt a day long process it takes aobut 10 minutes. It is totally worth it if you are legit. But if this XP came with another PC you bought and you used it on a different PC and activated it, that is why your version of XP is no de-activated.