Here's something I came across recently. It's a bootable CD with it's own OS for those times when your Windows installation is so messed up that you cannot even boot Windows.
It takes some technical skills to compile the CD but when that's done all you have to do is to insert the CD into the CD drive and let the computer boot from that. It starts a slimmed down version of XP Pro with a host of fixit utilities and even a couple virus scanners.
I haven't checked out everything that this does yet but it's certainly possible that this utility could save you a reinstall of everthing and/or recover some valuable payware aircraft or scenery that you forgot to back up.
http://ubcd4win.com/index.htm