Toothpick: whats wrong with the usual FDISK ?
FDisk doesn't delete the data on the hard drive, it simply changes the partition tables and possibly boot record. If you were to use FDisk to erase a partition, there are a ton of HD forensic applications that could easily extract all the data that used to be on the drive.
DOD has apparently set out standards on how data is to be destroyed on a hard disk. Short of physically destroying the drive, this is done by writing over the data many times, so that there is no original data remaining. Not only do they seem to be worried about data, but possible magnetic residue of some sort on the drive. I guess maybe there's methods of reading data off a drive that's only been overwritten once or twice, cause they seem to like writing over it 7 times....