New
#21
Go ahead and use the latest official ISO for the version you purchased (with SP1 and Refresh) in Step 1 of Clean Reinstall OEM then you can activate it with the key when it arrives.
If you are installing to a HD with no other OS on it now, leave the key blank during install and then afterwards do the quick registry workaround in Option 3 of Clean Install with a Upgrade Windows 7 Version to activate Upgrade version on a cleaned or blank HD.
If any other OS is on the HD now it should see it and allow use of the key during install.