How to delete all files on HDD except Windows OS?

Is it possible to delete all files on the HDD expect Windows OS itself? E.g. all custom files made by the user, leaving only the actual WinOS. So it would be a clean install without needing to reinstall vista?

Thanks,
Cameron.

The quickest way would be to create a new "administrator account", delete the current one and delete the files directories pertaining to it, then in the control panel, delete all the unused programs.

Okay, would it help to just uninstall every program i use, and then reinstall to it to regain any bloat?

Any other tips etc, for getting optimal cleaning preformance? Any applications i should use etc? ^^

You don't need to uninstall everything unless it's corrupt. After doing the suggested procedure, run these,

http://www.techspot.com/downloads/3160-advanced-windowscare-systemcare-free.html
http://www.techspot.com/downloads/132-ccleaner.html

Can I ask why do you feel you need to do all this???

Haha, i recently installed a new stick of Ram (2GB), i had a few BSoD errors a week or so after, after uninstalling a ton of unneeded stuff to try and fix it and doing a ton of graphics updates and windows updates i havent had one in the past 24hours, so i though, heck, lets whatever i can to help my PC without formatting / reinstalling windows. (Im not confortable with that, and i dont have my Vista install CD anymore, only my CD-Key on a peice of paper, and im not the kinda guy to pirate a OS - If your going to use something as much as you usually do, you should buy it, period.

If you played with your memory, then that's probably why the BSOD's come up.
Try running this.

I didnt play with it haha, ill try the memory test, thanks

Got 6 passes, 1 error.

what does this mean?

If you receive errors on your memory test, you should replace the module which gave the error.

Okay mate, thanks very much for your help.