Ok here is the deal, I baught windows 7 upgrade when it was first offered for $50. I have three machines, two running vista and one waiting to be put together. I want to have get all three machines working with my two legit oem vista disks and my soon to arrive windows 7 upgrade version. So my question is, when installing the win7 upgrade version does it de-activate the previous version (vista) of windows running on the computer. Can I call microsoft and say my motherboard fried and get a new serial number for the copy of vista that I used to upgrade to win7. Another alternative, can I use a non genuine advantage copy of XP as the base to upgrade to win7.