I tried to do a clean install of Win7x64 from my upgrade disc, which has worked fine the last 9 times, up until I came to register it today. It says words to the effect of: "This Key is only valid for ...

I'm looking at updating my Mac Pro's Bootcamp from Windows 7 Pro to Windows 8 Pro. My question is will my Windows 7 key still be valid? If so, I could update the Home Premium on my laptop to Pro... If ...