If you are worried about hard drive failure and feel reasonably competent tech wise, you could try
http://www.ultimatebootcd.com/. It has various free utilities that can be of help provided you have some idea of what you're doing.
WARNING: It is completely possible to totally wipe your hard drive with some of these utilities. Make a back-up of any data you might need. Read the instructions carefully, as many times as necessary to fully understand them, and then print them out. Then go make another back-up... just in case.
A scan of your hard drive's disk surface should let you know if your drive is starting to fail. One sign of such failure is the loss or corruption of files on your drive. It can take several hours, but it will save you from complete data loss if your drive fails completely.
BTW, these are all DOS / Command Prompt utilities; no Windows versions are included because the disk assumes Windows is not available due to catastrophe.
The warning above is simply to impress readers the software is not meant to be played with and is used at your own risk.
Most of the utilities will ask for confirmation before doing something permanent... On the other hand, the back-ups are simple paranoia. Most people don't back-up their data until something goes horribly wrong. And sometimes back-ups fail.
Edit: BTW, unless I've mis-understood locate32's functionality (I only took a quick look), Copernic Desktop Search, or even MS' Desktop Search is a more capable program. Locate32 is based on filename only. Both of the others I mention will look inside of files for applicable text. Results in a huge database though. (But they could, for example, let you know every book on your hard drive with a character named "Dan" in it.)