When I discovered I had purchased a counterfeit copy off of eBay (at $79), I contacted Microsoft about what was needed to make it legal. They said, "You must purchase another copy." There was no wiggle, no help from Microsoft. I purchased two copies of XP from Walmart at the same time in July 2005. One copy was fine and reported back as genuine. The other was not a genuine copy as reported back from Microsoft. Upon contacting Microsoft about the problem, they just said to go back to Walmart to resolve the problem. In other words, someone used my codec to register their illegal copy. How they broke the code is beyond me; however, Microsoft will do nothing at all to assist in this type of matter. Just buy another copy is their stance. Hope you have better luck with Microsoft than myself!