I would have to say that it comes down to two options, both of which
are in the open-source area, and have had great reviews, and several
If you are using Windows, then Eraser is probably the best available:
--"Eraser is an advanced security tool (for Windows), which allows you
to completely remove sensitive data from your hard drive by
overwriting it several times with carefully selected patterns. Works
with Windows 95, 98, ME, NT, 2000, XP and DOS.
Eraser is Free software and its source code is released under GNU
General Public License.
The patterns used for overwriting are based on Peter Gutmann's paper
"Secure Deletion of Data from Magnetic and Solid-State Memory" and
they are selected to effectively remove magnetic remnants from the
Other methods include the one defined in the National Industrial
Security Program Operating Manual of the US Department of Defence and
overwriting with pseudorandom data. You can also define your own
For everything else and as a means of erasing everything from a
computer (all drives, all data), there is Darik's Boot and Nuke:
--"Darik's Boot and Nuke ("DBAN") is a self-contained boot floppy that
securely wipes the hard disks of most computers. DBAN will
automatically and completely delete the contents of any hard disk that
it can detect, which makes it an appropriate utility for bulk or
emergency data destruction."
Both of these programs are open source, and have been peer reviewed several times.