I have an old HDD I recently fitted to a PC. It makes quite a noise, clacking away. I'm not sure if it's simply an old HDD with poor mechanics. I ran Speedfan to check the SMART data, run the short test, and the drive checks out fine. Perhaps you should try that or some other utility like the ones from WD or Seagate. However, I don't trust it and only use it for storing data that is replaceable. I mostly use for processing video and the end video gets moved elsewhere when done. You only have the one drive so it's more of an issue for you.
Edit: If you do not regularly defrag the drive, it may be skipping all over the place to find file fragments. Use one of the many free utilities such as Auslogics, Defraggler etc rather than the Windows one.
Remember Windows Vista and newer, all defrag the the drives regularly automatically. I really do not think that is the issue.
But my suggestion to OP is that if my hard drive is making that noise, even if it is bad mechanics, I'd spend the 50$ to replace it than be at risk at losing everything. I'd not use that drive until the replacement drive comes, and then do a disk clone. Easiest step to take.
If you cannot disk clone and the drive will not spin up and stop clicking at a constant pace (It must click at a rate, not randomly), then your hard drive is toast and I am sorry.
Edited by smerffed, 13 November 2012 - 11:32 AM.