This procedure for performing a secure disk wipe was recommended to me by an IT pro colleague who has experience working in US Department of Defense (DOD) environments where disks must be securely wiped before being reused.
Reboot the computer into the Windows Preinstallation Environment (WinPE) that has the SDelete utility included on it and partition and format the disk. Then run the following commands from the command prompt:
reg add HKEY_CURRENT_USER\Software\Sysinternals\SDelete /v EulaAccepted /t REG_DWORD /d 1 /f
sdelete.exe -p 3 -z -c -s -q C:
wpeutil shutdown
Note that I haven't tested this procedure yet so please use it "as is" with no warranties or guarantees.
Mitch is a ten-time recipient of the Microsoft Most Valuable Professional (MVP) award and a widely recognized expert on Windows Server and cloud computing technologies. For more information see http://www.mtit.com.