Clean Reinstall Windows 7 Home Premium x 32bit

When I purchased this generic computer I expected a clean installed version of Windows 7 x32bit. However what I received was a version updated from Vista. I have the Vista disk and a "Windows 7 Upgrade Option Program"disk, both with product keys.
My C drive (250Gb) contains only the operating system and programs, D drive (500Gb) is data only and F drive (External 1Tb) is used for backup.
I backup weekly including a system image. I do not have A "System Reserved" partition.
If at some time in the future I need to do a Re Format and Clean Install will I have to reinstall Vista, Update it and then use the Windows 7 disk or is there an alternative? I hope it never happens but I want to be prepared.

The Upgrade Kit which was offered with some Vista computers to keep sales up before Win7 was released has a bootable Win7 OEM installation DVD as required by MS of the manufacturers to participate.

As long as you still have the Product Key which came with the DVD you can clean reinstall without installing Vista first.

Thanks Cluberti.
I am the original owner. The machine was built by a local computer shop that is no longer operating. The Upgrade disk is a genuine Microsoft product not a copy.
I suppose what I am asking is it the equivalent of a retail upgrade disk or the eqivalent of an OEM version.

I believe the Upgrade Kits which were offered as an incentive to keep selling Vista computers are OEM version. We have helped do several hundred of them here.

Thanks Gregrocker. Really appreciated.
I intend to copy the tutorial and keep it handy.