Full harddisk wipe
1. Darik's Boot and Nuke
http://sourceforge.net/projects/dban/
2. Data Lifeguard Diagnostic for Windows
http://support.wdc.com/product/download.asp?groupid=612&sid=3
Data secure delete under OS
1. Eraser
http://eraser.heidi.ie/
2. How to Overwrite Deleted Data using the "Cipher" Command in Windows
http://www.sevenforums.com/tutorials/276046-cipher-command-overwrite-deleted-data-windows.html
3. SDelete
http://technet.microsoft.com/en-us/magazine/2009.08.utilityspotlight.aspx
http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx