Very easy to do... (Score 1)

First thing I would do is purchase a hard drive enclosure. They run about 30-40 dollars and will hook up any ATA/IDE hard drive via USB 2.0 Some hard drives that have failed due to read failures will not be able to be hooked up in this fashion, but otherwise you wouldn't have any problem. After you have ensured there is no data worth retrieving, there is a handy program called boot and nuke that will write over every sector with random data, ensuring that there is no viable information left on the hard drive. Afterwards, feel free to resell or recycle the hard drives in whatever fashion you deem fit.