I destroy my old data using what storage experts call a
“block-erasure utility” such as Darik’s Boot and Nuke. DBAN
overwrites each block on a computer’s hard drive several times–up
to standard levels specified for the Royal Canadian Mounted Police
and the U.S. Department of Defense.
DBAN can create either a bootable floppy disk or an ISO file
that you burn to a CD. Once you boot from the startup disk (you may
have to tweak settings in your system’s startup program to boot
from the floppy or CD), just a few keystrokes will begin blowing
away your data.
Note: This program is donationware. It is free
to try, but the author accepts and encourages donations towards