I was preparing my old laptop for resale. So the first thing I did was to reinstall the original factory image onto the laptop. But this still left me worried that I may have data that is still reachable in the empty space. So I was looking for a HDD Eraser that would cleanup the empty space on the hard-drive.
I found “Hard Disk Scrubber” (http://www.summitcn.com/hdscrub.html) and it allows you to secure delete a file(s), a folder(s) or the empty space on your hard drive.