Hard Drive Inspector
Who's looking out for your PC's hard drive? Hard Drive Inspector is always on guard, monitoring all your drives for spin rate, seek time, and almost 20 other potential problem spots. Hard Drive Inspector gives you technical data, including the drive model, firmware version, and serial number, all things you'll need to know when calling for warranty support.
It displays the hard drive's temperature in the system tray. If the drive gets too toasty (I have mine set for 120 degrees Fahrenheit), the program can send you an e-mail alert--or, better, automatically put the computer in Standby mode.
You can view a summary health report, which typically has enough information for most users; the S.M.A.R.T. report has the details. The program costs $30, but you can download a 15-day trial version of Hard Drive Inspector to get a feel for the tool.