Why, of all the pieces in a computer, would you think it is the hard drive? Have you checked your cables? If you really suspect that its the HD, I'd replace the connection cables with known working ones first.
When hard drives die, IF they give any indication, is either loud clicking, bad sector spreading, repeat access of a sector (this goes with load clicking), or bad motor (where the HD tries to spin up and can't, and it sounds like its having an asthma attack)
Any more too the list? =p