DH and BIL have mentioned before that the only way to rid the hard drive of private/sensitive info would be a hammer. I think they even said fire would still leave
something there, so if you're throwing out the whole computer, just keep the hard drive until you can smash it into teeny tiny bits. I'd even throw out only a few of those at a time, different garbage cans/bags or whatnot - that'd be my personal "failsafe"
