Hi, my computer was running xp and i brought vista upgrade for it. installed it and all worked fine. Then my hard drive blew up and i had to get new one, i used boot cd's to get computer to run to install master cd's of which i dont have cos the info was stored on the now blown up hard drive. If i boot computer with vista upgrade cd, it works up til point when have to enter product key, when i enter product key, it says the product key cannot be validated. So what can i do to fix this?