When I was with DOD, in the IT Dept. we used BCWipe at the time.
Spybot Search and Destroy (free) has a secure shredder program in it that can be configured to do up to 99 passes
From SB Search & Destroy
Secure shredder tool Tools
The secure shredder is a tool to finally get rid of files without any further possibilities of recovery.
Shredding is simple â€“ drop some files from the explorer into the list (or add some using the context menu of the list), select the number of shreds, and click Chop it away.
Usage tracks that are in files will be shredded using this tool, too, using 5 passes.
The first 5 shreds are using pre-defined bit patterns that should make even hardware recovery impossible. Any further pass will use a random bit pattern that is changing every few bytes.
Please notice: one pass is not enough to shred a file, as the heads of your hard disk won't hit the same track 100,00% of the time. There are small differences of a few Âµm that will allow pros to reconstruct even overwritten data. That is why multiple shreds are necessary, and why different patterns should be used.
Warning: This tool is designed to remove files so they cannot be recovered again! If you use it, be aware of that!
You do not need to use this tool to remove spyware or usage tracks. Spybot-S&D will take care of shredding them on its own.
Disclaimer: I tried my best to finally shred every file given to this tool. But I can't guarantee that files will be unrecoverably extinguished.
You can find the secure shredder tool by choosing Secure Shredder from the Tools section in the toolbar to the left.