You should be able to connect it to another machine and access the files if the drive is functional and not infected. After you do backup your files you might want to try a repair installation that can reinstall Windows but leave your programs and data intact like THIS.
You can get a adapter like a Vantec CB-ISATAU2, you can attach your drive as a slave to another computer. You can then run your virus scans and malware scans on the drive. Backup your personal data on to DVD or another drive. Once your sure you have it clean you can put it back in your computer. You may need to roll back the O/S to a date before you got infected if any O/S files were damaged.