Do it the "right" way. Use the Secure Erase command added to the ATA and SCSI interface specs. http://cmrr.ucsd.edu/people/Hughes/SecureErase.shtml. Funded by the NSA until recently.

The only effective change to security since 9/11 happened the moment the world learned of it. Never again will the passengers of a plane allow it to be turned into a guided missile. If I have to tell my children that only mommy, daddy, their doctor, and oh yes, any government goon who flashes a badge can touch and rub their privates (and if you tell the government goon 'no' he'll sue and there goes your college fund) then we've destroyed our country far more effective than any act of terrorism could.

The U.S. legal system can be described as many things, but certainly not as having a firm grounding in reality.