If you have a Windows machine, use the free Eraser utility:
If you are using a Macintosh computer, wiping your hard drive is even easier. Open Disk Utility. Under the "Erase" tab, click the "Security Options" button and select how many times you want your disk erased.
To erase your main startup disk, you'll need to boot from a different disk. In Mac OS X, you can boot from your Mac OS X install disk and then select Disk Utility from the "Installer" menu.
Note that simply reformatting the disk or reinstalling the operating system will NOT delete your data. You need to overwrite your entire disk many times using the tools I mentioned above. In fact, the only way to be sure you data is truly safe is to completely destroy the hard drive by shredding it into tiny pieces. However, the eraser tools listed above do a very good job if you don't want to destroy the drive.
After you've wiped your hard drive, reinstall the OS using the install CD or DVD. Then sell your computer on MarketWall:
MarketWall is a free way to sell your old stuff to people in your area.
· 1 decade ago