Don't do anything with the computer.
You have basically two options at this point.
Option 1, use a file recovery program on the HDD. This will pull all your files, although they'll be unsorted (all of them). It's a messy headache, but you'll recover around 99% of everything you have.
I'd recommend installing windows on another drive, and putting your corrupted drive as an external (or secondary drive). Or install linux onto a thumb drive and pull files that way.
Option 2, repair windows. I'm not sure what your specific problem is, but it'll involve some troubleshooting. Be careful about what you do when fiddling around, as you can overwrite files. Try booting off a windows CD. There's also a command, system file checker, this saved my ass last time I had a problem.
Key point here, fooling with your drive too much will mess files up. Pick an option and go for it. If oyu have spare storage space, pull all your files with a recovery tool, then try to repair it.
Also, when you're done with all that, send me message and I can hook you up with a pretty good backup tool, for the future.
I'll defer to the more tech savvy people at this point