Secure Delete

On high security systems its a good idea to perform a secure delete of files or regularly write zeros to your free space to remove what remains of previously deleted files.

Secure Delete Windows

I came across this utility which seems to do the job perfectly. http://technet.microsoft.com/en-us/sysinternals/bb897443

Usage:

Securely erase a drives free space

sdelete -p 5 -z c:

This will write random strings to the free space on drive C: for 5 passes.

-p = Pass
-z = Zero free space

Securely delete a file or directory

sdelete -r c:\temp

This will securely delete c:\temp and all its sub-directories (1 pass)