Time to answer a question from the Hardware 2.0 mailbox:
I have dozens of old hard drives about the place from old systems. Some are faulty, while others are the product of upgrading to bigger storage. I've now been ordered to get rid of these drives.
Can you suggest a way to securely wipe a hard drive?
Yes, I can. In fact, I'll give you a way to do it with hardware or software.
See also: Video: How to destroy hard drives
The best hardware solution I've come across is WiebeTech's Drive eRazer Ultra. This is not a cheap solution--the kit will set you back $249--but it will allow you to erase both SATA and PATA hard drives quickly and securely without having to tie a PC up to the job.
If a hardware solution is a bit too pricey for you--and unless your job involves erasing hard drives, then it probably is--then an excellent software solution is to download Darik's Boot and Nuke (DBAN) and use this to erase the hard drives. DBAN is free hard drive 'nuking' software that allows you to securely wipe the data off your drive using a variety of overwrite patterns.
This will take a long time--longer if you choose the more secure erasure techniques--but it does a thorough job.
There are two other things worth bringing up.
First, if you come across any drives that appear to be dead, remember that they will still hold information. If it is sensitive information, then these drives will need to be destroyed. A quick way to do this is to open up the drive, remove the platters, and run them over a strong magnet.
Alternatively, you can use a more dramatic method to destroy the drive, such as a sledgehammer, grinder, or even thermite, for that matter.
If you have solid-state drives (SSDs) then remember that these can be almost impossible to erase securely. The best way to do this I find it to use a whole-disk encryption tool--such as TrueCrypt--to encrypt the entire drive. If you use a really long key, then without this any data on the drive will be unrecoverable.