Organizations and individuals replace computers for all kinds of reasons, and the machines often end up in yard sales, auctions, or local computer resellers' shops. Identity theft and misuse of personal information is often an unexpected consequence of failing to effectively erase the data on old hard drives. Although this may sound unlikely, it's even feasible to continue to read the "signature" of old hard drive data after someone has overwritten it.

Whilst the most secure method (and possibly most satisfying) is a few well placed clouts from a club hammer, this does little for the re-sale value of the machine.

How can you ensure your data is wiped?

At the very least do a low level format of the disk (fdisk), then re-format and install the operating system. This will remove the data from your drive, although a determined forensic study can still retrieve the data from residual magnetism within the drive.

A better solution is to use a package that over-writes the disk several times with random data (such as http://dban.sourceforge.net ), follow this up with an fdisk and re-install and you should be OK.

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