deltafoxtrot,
You could spend many hours and days messing around, trying to get your OS back and there is a chance you will not get it back to 100% again. I think it would be worth doing a fresh install. Just have all your drivers downloaded before you start the install and it will save you a lot of time.
Get the latest drivers from the net and have them on a CD so you can load them as soon as you finish the install.
Take Care,
Richard