You might want to think twice before simply giving away your old computer or smartphone.

With Windows 8 scheduled to come out this year, many people will be ditching their old Windows XP computers in favor of a newer model. However, your computer can still carry valuable personal data, even if you think you've wiped it clean. And it's not just computers; smartphones, particularly Google Android phones, can also hold on to personal data even after you've reset the phone to the factory default settings. And these devices make their former users all too vulnerable to identity theft.

Consumers are storing more personal and work-related data on personal devices, at a time that electronics makers are enticing them to upgrade to faster, more capable smartphones, tablet PCs and e-readers.

Meanwhile, it's not always easy to wipe older devices clean, and any data left behind could have tangible value in a cyberunderground that revolves around online exchanges in which stolen data gets quickly converted to cash, says Mary Ann Miller, financial fraud expert at Nice Actimize, a supplier of banking security systems. "Security should be a key consideration from the moment you acquire a device — and when you dispose (of) it," she says.

While Microsoft and Google devices still contain a lot of information after wiping the system clean, Apple and Blackberry devices do a much better job of deleting all personal data.

If you really want to be safe against identity theft, the very best thing you can do is destroy your old device completely. But if you can't bear to take a hammer to your old cell phone, at the very least, make sure you're extremely throughout in wiping all sensitive data from your system.