When you are ready to sell your older computer system and buy a new system, it is important to remove any personal files or information from the old computer before putting it up for sale. This will ensure that your privacy is protected and other people will not have access to items left on your old computer. Simply deleting files off your old computer will not prevent others from retrieving them. More in depth methods must be employed in order to make sure the new owner of the computer will not be able to retrieve your old personal files.
Find and transfer all of your personal files onto a writable media such as a DVD, CD-R or USB drive. Double-check that all the files have been transferred and delete the original files from the computer.
Use a hard drive cleaning program to completely rid the computer of personal files and information. Consult the hard drive cleaning software's installation and operation instructions in order to use the software properly. Check out the Resource section for links to some of the more popular hard drive cleaning programs available.
Reinstall the operating system with the computer's original system restoration software. This method will completely erase the information on the old computer and restore it back to the original manufacturer's configuration.