Identity thieves could be tempted by the huge number of hard drives that are being dumped with confidential data intact, says Which? Computing.

The consumer protection publication said that it's so easy to recover data from dumped drives, that the only solution is to destroy them with a hammer. The publication showed how easy it was to retrieve sensitive data from unwanted PCs by buying eight second-hand hard drives from online auction site eBay and trawling through them to see what confidential information could be uncovered.

Using easily obtainable free software, Which? researchers recovered 22,000 'deleted' files, including images, music files and spreadsheets.

Which? Computing editor Sarah Kidner warned that the risk of falling victim is high as the average UK citizen is worth an estimated £85,000 to an identity fraudster. "PCs contain more valuable personal information than ever as people increasingly shop online and use social networking sites."

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She said that brute force was often the only answer; "It sounds extreme, but the only way to be 100 percent safe is to smash your hard drive into smithereens".

Which? Computing research closely mirrors that of University of Glamorgan's carried out last summer. The BT-funded research analysed 317 second-hand hard drives purchased second-hand and found that 23 percent of business machines contained enough information to identify the specific company that had owned them, and a shocking five percent still held sensitive business information.

If destruction sounds too extreme, there's always the option of encrypting all the hard disks. This could be an expensive option and not always reliable as researchers from Princeton University found last year when researchers showed that encryption such as BitLocker could be cracked.

See also: How to safely dispose of an old PC