A while ago I wrote a three-part article on backing up and saving precious data. This is about how to destroy data so it can never be recovered.

Since Christmas was just a few days ago, some of you may have been lucky enough to get a new laptop or personal digital assistant (PDA). I received a lump of coal, and I will treasure it for as long as I am warm. Anyway, back to your old gadgets. Now you find yourself in the position of having to dispose of that old computer, and you need to be aware it contains everything a bad guy needs to wreck your life. Identity theft is the new black. Every other day we hear stories of people finding their bank accounts cleaned out, their credit ratings blown or their private, um, shall-we- say Paris-Hiltonesque home movies getting a zillion hits on the internet. This can be embarrassing, not to mention highly annoying. Which brings me to my point: before getting rid of that old machine, you need to take steps to ensure that any of the above scenarios don't happen to you.

When getting rid of an unwanted machine, it is tempting to just delete your vintage erotica collection and empty the recycle bin, but anyone with a smidgen of knowledge can easily recover anything that has been deleted this way. This is because data, when deleted using the standard Windows utilities, is not actually deleted. Oh, it may disappear from view, but it is alive and well on your hard drive. It has only been marked for deletion, which means that Windows, or any other application, can feel free to overwrite your "deleted" files with other data. There is nothing wrong with this, except that with today's huge hard drives, that data might not be overwritten for months, if not years. Even if it is overwritten, it may still be recoverable. Obviously this is not a suitable way of ensuring that your sensitive documents are gone for good.

"So how do we do it then?" I hear you ask.
Like all things computing, there are various ways of achieving the same end. One way is to sell or dispose of your old machine without the hard drive. Because hard drives are relatively cheap these days, this is a viable option, although the resale value of a machine without a hard drive or operating system is low. Another way is to securely wipe the drive of existing data using specialist software and install a clean copy of your operating system. This incurs extra work and expense, so it is not the most popular choice. A variation is to buy a new hard drive and install the operating system on that, leaving the old drive intact as an archive or backup. Since this also involves spending money on something you are going to dispose of, it isn't popular either. Unfortunately, there is no such thing as a free lunch, and sometimes peace of mind costs money. A compromise may be reached by using some of the file-shredding tools available to eradicate your personal data from the drive, leaving just what needs to be there. This requires a certain level of knowledge, because once the data is deleted, there is literally no way of getting it back. Also, expensive software applications such as MS Office or Photoshop leave their registration details behind, even when uninstalled, and this information can be easily retrieved and used by subsequent owners.

What would I do? I would sell the machine without a hard drive and take the hit. In the end, it may be that you have to give the machine away for a song, but isn't that better than finding your smiling face on YouTube or the evening news? If you have a gadget such as a PDA or a Blackberry, there are also various strategies available to erase your data for good. Hit Google for the best way to go about it for your particular device. One legend has it that with a Blackberry, simply setting a password on it and entering it 10 times incorrectly wipes all data from the device. I don't know anyone who has actually done that, but it sounds like it should work. Another idea would be to go back to the store you bought the device from and ask the team there. They may know how to do it.