1. Don't download ANYTHING...leave your computer alone...shut it down...the files are still there, they are just disassociated w/ the file structure.
2. Download a file recovery application on another PC (Google "data recovery software" or something along that line to find a whole slew of options...I'm trying to find the link to a program that I used not to long ago to restore a corrupt partition...it cost me about $70.00 US...well worth it.)
3. Pull your hard drive out of Computer A and make it a slave (if it set as master) in Computer B (there are tonnes of resources on the Net to aid you in this if you already don't know how).
4. Run the file recovery application on your drive via Computer B.
5. If all went well, then you SHOULD be able to salvage almost of your files.
6. Put Disk back in Computer A...
Best of Luck,
Voyd
EDIT: Looks like Graf beat me to it...
EDIT #2:
http://www.recoveryfix.com/recover-windows-data.html
You can run it for free and see how successful the recovery will be...if it's worth your while, you can then purchase a license you recover all of the non-corrupted files found...I'd try the freeware application that Graf had suggested first, though.