ahhh... my world.... Just deleting files normally (moving them to the Recycle Bin, then emptying it) does not securely delete them...until they've been overwritten they can still be recovered using specialized software. Thus, before selling the computer, the best way to remove all the information on you computer completely is to remove your hard drive and drill a hole in it and replace it with a new one. If you are unable to do that, I would format the hard drive at least three times then reinstall the operating system.