Just for clarity can you install it using that CD Key at all? Like right now are you stuck at the installer or are you on a "You have 30 days to activate."
Frankly if you purchased a copy of Windows 7 OEM and they sold you Windows 7 upgrade then you've been ripped off. Windows 7 upgrade is worth less and has licence restrictions.
Im stuck on the Install. Back on with Microsoft support, been 20 minutes already and still on hold.