Question : Windows 7 Licensing

I two copies of WinXP - the Home version that came on my Dell desktop & an OEM WinXP Pro I replaced it with.  Therefore, both of these versions of XP have been activated with my Dell.

I have a new intel-based Mac 7 on which I'd like to install Windows 7.  (I have installed a program called Parallels that allows you to run Windows on this Mac).  

When I install Windows 7 on my new Mac, can I use either of my WinXP versions if the installer asks for a previous version's Product Key?  How does the upgrade version know if you have an earlier Windows version?

Answer : Windows 7 Licensing

leslieinva: In case I was not clear above (I might have confused you): both versions of Windows you own are OEM. Nevertheless, the one that came with your Dell (Home)... Cannot be transferred. It is not legal.

The one your purchased later.... The XP Pro, would be your legal justification of using the upgrade. Again.... Windows 7 does not check...