I have a laptop that originally had W98 installed, and has an XP Pro upgrade disk and product key. I wanted to do a clean XP install. Since I already have an XP Pro CD (not an upgrade version) with SP3 slipstreamed, I used this instead of the upgrade CD, but the product key that came from the upgrade disk was declared invalid during the installation. I continued installing without entering a product key. Is there any way to persuade the installation to accept the product key from the upgrade CD? Eg a registry change? If not, is there any way for me to make another CD with SP3 slipstreamed that will accept the key that came with the upgrade CD?