I just got this reply from Digital River:
"The Windows 7 offered in this promotion is a full version. You can
install this product even though you do not have a previous Operating
System installed in your computer or if you want to make a multi boot
using Windows 7. The "Upgrade" included in the product name is just
because Windows 7 is the latest Operating System Windows developed.
For more information please contact our pre-sales department at:
1-800-642-7676"