If the drive still works, but simply needs disposing of
Use DBAN or the Linux 'wipe' command from a LiveCD

If it's broken the only totally accepted way is to melt all the platters into a lump, and burn the PCB.

NB: The above is only really needed for the really unforgivable porn or disks containing people's details and such. But if it's at work there's plenty of places you can hire a degausser.
( Cadmus has teh uplikn coeds at, Wed 23 Mar 2011, 23:29, Reply)