Here's a good case-in-point of why physical destruction isn't always the best solution. While speaking with a manager at a company (I do work for them from time to time), they were going to decommission a computer that was being replaced. Because it could contain personal information they were concerned with just getting rid of it without sanitatizingn the hard drive. One of the manager said she'd planned on taking a hammer to it.
My personal thoughts are first, why destroy a perfectly good piece of hardware needlessly. But more importantly, "physical destruction" shouldn't imply just damaging the drive beyond use. Granted busting up the controller hardware will ensure it's never used in a conventional manner again. However, it's very LIKELY (depending on how much damage is done to the platters) that data can be recovered thru laboratory means. That also includes drilling holes; you've only damaged the areas drilled away--nothing else! This individual (like many other non-IT management) is ignorant to the inner workings. I'm glad this article touched on this point. Also, I've taken apart several hard drives and I will say this: those platters are strong! Also don't think for a minute that such recovery is far fetched. There are plenty of companies that will perform this type of recovery for anyone with money (generally a couple hundred to a thousand or more).
In my opinion the best approach is employing full drive encryption on all drives w/either sensitive data or portable drives (notebook, etc). Then you can simply delete the encryption keys off the TPM and the data is made virtually unrecoverable--providing of course you use a good encryption algorithm. Vista Ent./Ultimate & Win Server 2k8 have BitLocker. Use AES with a 256-bit key for maximum protection.
The other option is using the secure erase features of hard disks or overwriting the disk. With overwriting, there's a couple of things to keep in mind. 1.) Make sure to choose a well tested, proven program that can be booted from external media (CD, floppy, etc). This ensures all the space is actually available for overwrite. I would recommend performing at least 3 passes (0's, 1's, psudo-random). If you're really paranoid or handle other people's sensitive data using the 35-pass Gutmann method (it should also ensure each track is completely overwritten). The only crevet, it's time consuming. It's not a big deal though--just set it up and walk away.
Here's a good page with more info:
Hope this clears stuff up!
