Erase Your Hard Drive

People give their old PCs away to family members, charities, and some end up at the local PC repair shop without ever being properly wiped clean. Everything stored on your PC is on the hard drive. There was a two-year experiment done by MIT graduates Ali and Eman where they collected 156 hard drives from various places (the web, ebay, PC shops, and businesses). Out of the 158 drives tested, 129 drives worked and hardly any of them were properly wiped clean. There were thousands of credit card numbers, private "adult" stuff, love letters, you name it, that was completely recoverable on these drives.
Most people believe that deleting data and then cleaning out the recycle bin does a sufficient job. This is NOT the case. When you delete something in windows, it just marks it to be overwritten. There is also a misconception that formatting a hard drive permanently erases stored data. This is also not true, a format just reconstructs the allocation table and checks the blocks on the disk. It does nothing actively to remove the data; it simply leaves it "unprotected". With both of these scenarios, if you have the right software you can recover data thought to be unrecoverable.
So, how do we erase this data on a hard drive for good? You can physically destroy the drive but that's not as easy as you think and you would be amazed at what people can recover data from. There are cases where people have drilled holes in the platters and it could still be recovered. You can take it to a PC repair store that has a Degausser that removes all the magnetism from the drive leaving it useless for good, but this can be way too expensive to justify the price for the common end user. You can write Zeros to the drive with the utilities at the hard drive manufacturer site and that will stop most people, but experienced users can still recover it.
If you don't want to destroy the drive, and are concerned about keeping your privacy then check out these two free programs that can take your hard drive to a state of non-recoverability...