Erasing Data on a Dead Hard Drive

[rawfuls]

Well, my parent's hard drive finally took a dump, and although I always told them, don't save any credit card or passwords, etc, on a hard drive, in case if fails they did. And some other data we'd rather not get out, into a criminals, or normal persons hands (No, not hand pr0n). But in all seriousness...

I hit up Seagate and we have a 5 year "limited" warranty, and our drive IS covered by the warranty.

HOWEVER, I do know how to format, and tri-format and whatnot, but this drive has imploded... It won't get recognized, at ALL!

Through BIOS, through an enclosure, through a SATA -> IDE -> USB and everything else.

When I try booting off of it, or WITH it, the BIOS will not go through, so it doesn't past P.O.S.T.....

Before we send it in to get a new hard drive warrantied, I want to get this stuff off the disc, and deem it even more useless, because who knows what Seagate can pull out of their.... mouth.... and to find the credit card, password, and such information.

Any advice?

I've heard passing a magnet over would work (well, it's a myth), but I've also read that it doesn't do anything at all...

BTW: I'd like to keep the hard drive in one piece, without voiding the warranty, and also, it's a SATA drive.