Hi, My computer notified me last night that my version of Windows 7 Ultimate may be a pirated version! And I think it intends to shut windows down on my computer if I do not provide an Activation Key that it likes. I bought a Full install (OEM) version of Windows 7 Ultimate last night and should receive it in the mail within the next few days. My first question is: Can I use the Key coming with the OEM disk to plug into my current installation and validate. Or will I now need to re-install windows fresh? Also, I know that OEM versions have a one use key, and cannot be used on another computer, which is a problem for me (as I intend to build a computer for my kids) My Second question is: If I buy a upgrade version, can I use that on top of the OEM version? For instance, I use the OEM key tonight to validate my copy of windows. If I go buy a upgrade version later, can I use them both to install Win 7 on several computers? as I know that Windows 7 is a pain to try and install on a clean drive. Or, should I just bite the bullet here and buy a Full install version of Win 7 ultimate, that is not OEM version. (like 300 bucks) ?