Here is a fantastic program that only reads your disk drives, it never modifies anything (after installing). It reads the low-level S.M.A.R.T. indicators of your disks and warns you when things are about to go bad. Silently running in the background WindowSMART will alert you when your disk is about to fail!
BEFORE your disk crashes, you can get popups, emails and even notifications on your phone! Give you time to make a backup and replace the disk.
Great program, highly recommended!
A very nice discount in the comments below - make sure to read!