If you have a second PC move the disk over to it and make it a
secondary drive. See if it can look at your data (the operating system
must be equal or later version and patch level to avoid file system
problems. Don't write on the disk, if you can see your data. Copy
your files off, reformat and build your system from scratch.
-OR-
Burn yourself a Knoppix (Linux) CD (download from
http://www.linuxiso.org/).
Knoppix boots from the CD and lives in memory. It has NTFS and FAT32
drivers and will try to mount your hard disk, read-only. If you see
your windows files it tells you something, and gives you a chance to
copy the files off the C drive to something else.
It recognizes most network cards and USB devices. In principle
you can burn your data into a USB CDR device but if it makes
temp files it's limited to RAM size. You need something like 256MB
to run Knoppix.
A USB-connected disk drive should work fine. I've FTP'd user data
from windows machines that became unbootable (most recently when
Windows Update gave me a new driver that ruined my day)
I've had clients that paid $4000 to recover data from a dead server
disk because they were too lazy to put tapes in the tape drive. $500
sounds cheap.