Erase files securely and completely with DeleteOnClick
DeleteOnClick is a free program that deletes files completely in one click and the data becomes unrecoverable.
Once a file is ‘Securely Deleted’ no one can undelete it.
Features: Any file can be securely deleted, except files that are being used by other programs. * Follows the U.S. DOD 5220.22-M secure file deletion standard. * Completely deletes files in one click. * Compatible with both Windows XP and Vista. * Files deleted using DeleteOnClick are permanently erased and can never be recovered. * Deletes files on any physical drive visible by Windows. * A Confirmation warning allows the users to change their mind before deletion. * Delete progress shown.
A commercial (pro) version will rename your files before deletion using random names, so that anyone trying to undelete them will not be able to see the original names.
(Check also this free Shredder Desktop Gadget)