To recycle your old computers safely, wipe out all the personal information on your hard drive and then dispose of the hardware through a reputable computer recycling service such as those offered by Apple, Best Buy and Dell. In some states, it is illegal to dispose of computers in a landfill.
The Delete command of your computer doesn't erase information completely, and it is still possible for people to retrieve your deleted information. The most secure way to delete information is to overwrite it multiple times using a program that is compliant with U.S. Department of Defense guidelines, such as Darik's Boot and Nuke or WipeDrive.
Once you have removed all your personal information from your old computers, you can donate them to organizations such as the National Cristina Foundation, Goodwill and Free Geek. Both Goodwill and Free Geek provide tax receipts for your donations. In addition, if Goodwill and Free Geek can't refurbish or reuse your old computers, they recycle them for you.
Alternatively, you can recycle your old computers through a reputable electronic recycling service such as Best Buy's Recycling Program, Dell Mail-Back Recycling, or the Apple Recycling Program. Best Buy accepts old computers of any condition at all of its stores. Dell recycles any brand with the purchase of a new Dell product. Apple's Recycle Program accepts computers of all brands, and if your old computer has a resale value, you receive an Apple Store gift card.