The program can show you a constant visual and written representation of the state of your hard drive, which will usually be in perfect health (modern hard drives are very resistant).
However, the best way to use the program is to minimize it so that it just appears on the taskbar. Then, you can just hover your cursor over the program icon to see information about your hard drive's temperature and health.
HDDlife for Notebooks is an interesting application which will let you completely stop worrying about possible hard drive failures.
15 day trial.