First of all, destroying the hard drives doesn't mean you have to destroy the entire computer. I think you are confusing the word "hard drive" for that big box you plug your monitor and mouse into. That's not the hard drive, that's the computer. The hard drive is a device inside the computer which stores data. You can destroy it without destroying the rest of the machine. That being said, yes, you can erase all the information off of it without actually destroying it if you want to. There is plenty of tools available for free on the internet, just go to Yahoo and type in "free hard drive erasing software". You can also physically destroy the drive. Remove it from the computer, and destroy it as you see fit (personally I like blowing them up, but thats just me) Just however you decide to destroy it, make sure the metal platters inside are destroyed, or at least de-magnetized.