I have a feeling you'll be buying a new hard drive soon. But first, download a hard disk test utility and use it to see if it's truly dead. I keep a copy of Rescatux [http://www.supergrubdisk.org/] on a CD for just these occasions; it does all kinds of fixit jobs like deleting passwords or moving all yourdata files off a failing HDD.
If you don't want to either buy a new hard drive or new computer, you can get some more life out of it by booting PuppyOS [http://www.puppylinux.com/] off a CD. It runs pretty fast and has a lot of built in apps. You can save data to a flash drive.