Good Grief! You left one install on for 4yrs.! I can imagine all of the accumilated crud in the registry itself let alone all over the drive!
(there's no better feeling then a fresh clean install of Windows. )
Yea until you find out you needed something from the prevous install
Let's get this party started, I'm sick of begging you You make me dead inside which I give to you
Let's get this party started, You make me feel inside I want to be the one to make myself sane
That's why there's a files and settings transfer wizard for creating backups. Once the fresh copy is on you simply import a backup. Of course that's known as the slow ketchup there.
The simple solution is regular backups at all times in case Windows gets foobarred, you reinstall for a dual or multi boot, or even a worst case drive crash where everything is safe elsewhere already. I think cbtech73 had already thought of those things there prior to proceeding however.