OK, do you have a system recovery/installation disc of any kind. If you do, then that should restore your PC to as when bought. Touch wood, since the days of '98, my PC('s) have never wholly crashed, and I have always been in a position to reinstall if need be.
Backing up the stuff that wasn't on it that you want to safeguard (DL programs, photo's, mp3's etc) can then simply be copied over as and when you want.
I actually prefer this to some of the software options, as at least you are in control all the time.