Clean install Windows 7

My Hdd died and i bought a new one Dell supplied me with a Vista disk so that this could be loaded before using my W7 upgrade disk. I installed both fine and ran system image restore. I then realised that one of the problems I had before, i.e. SP1 wouldn't install still, so I decided to do it all again before making sure that I had all the updates before backing up old files (which I decided to do selectively instead of restoring a full image. This time, W7 hung and wouldnt fully install. I never got as far as putting in my product code. I then tried to do a clean install from the upgrade disk (as described above) and several times I have failed.
Please could I have any suggestions?

I'm sorry Dell wasted so much of your valuable time reinstalling Vista and not providing you with the necessary Win7 installer with SP1 to save hours of updating.

Everything you need including the latest official installer is here to get a perfect Clean Reinstall - Factory OEM Windows 7.

In your case you would normally leave the Product Key blank during install, then afterwards use Option Three or Four here to activate Upgrade version on a new or wiped HD: Clean Install with a Upgrade Windows 7 Version. These workarounds were designed with your situation in mind, to save all of the trouble Dell caused you.

However if either OS is still on the HD, then when you boot to reinstall with the latest 7 installer it will likely allow you to use the Upgrade Key up front since the installer will see an underlying OS and not a blank HD.