not knowing what kind of hard drive you have, you could just use a tool kit like the one Western Digital offers that can write zeros to the hard drive overwriting everything that was on there perminantly and also have other tools to test the hard drive and repair errors. This specific package is the DLG Diagnostic tools that can be downloaded under the diagnostics section from the link below.
http://support.wdc.com/download/#windlg
Bookmarks