Recently McAffee and Craiglist got together to see how much personal info was passing in the hands of ID thieves when someone sells an old computer. They purchased 40 computers, a combination of both desktops and laptops.
The results may surprise you, even though the sellers thought they deleted all personal info. In 20 of the computers (Keep in mind they did brought all the hard drives to a data recovery service). They were able to get enough personal info, to steal someone ID if they wished. In one case where the computer came from a business they were able to get enough info to steal the employees personal info.
They advise if you plan on selling an old computer, first get a program to completely erase the hard drive. They can be found very easily with any search tool and usually come as a bootable CD which you burn the image file to. Then reinstall the OS along with any program you wish to include.
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