Second Booyah's suggestion to run a full scan on the drive. If you don't have the diagnostic software for your hard drive, grab and burn an ISO from
http://www.ultimatebootcd.com and chose the diagnostic from your drive's manufacturer.
If the drive doesn't appear in your BIOS listing, you're pretty much screwed. Unless you can replace the IDE controller board on the drive, (and that's the drive's only problem), you won't be able to recover the data yourself.
If the drive shows up and works OK but the filesystem is corrupted, or the drive shows up but with bad sector information, there are programs you can use to try and recover as much corrupted data as you can.
This page has a listing of what mostly constitutes the best free data recovery programs available. For most of those, like PC Inspector and Drive Rescue, you'll want to hook up the hard drive to another working computer so you have a working drive to copy the recovered data to. If you don't have a separate computer to use, you can run some of these programs from a Bart's PE disk such as the
ultimate boot cd for windows, which actually includes TestDisk and PC Inspector.
Most of the time, though, I suggest the commercial data recovery tools over the free ones. GetDataBack is an excellent recovery program that I've used consistently to recover corrupted data. It runs from a working Windows installation, and comes in a FAT and NTFS version. You can download it to see if it works for your drive, and then purchase a key to copy over the recovered data to a good drive.
The other I suggest is SpinRite, which runs completely from a bootable floppy or CD and analyzes a drive sector by sector to read and recover data even from sectors that have failed. It doesn't have a trial version, but I believe you can ask for a refund within 30 days if it doesn't work out for you.