If your computer is less than five years old, first consider donating it to a school or non-profit organization. If you don't donate it, you should recycle your computer because it contains substances that should be disposed of properly such as lead, mercury, and PCBs. In addition, computers contain valuable materials that can be recovered during the recycling process (such as copper, palladium, and tin). Recovering these materials through recycling, rather than manufacturing new materials, conserves natural resources and avoids the pollution caused by manufacturing virgin materials. Go to Earth 911 to find where to recycle computers in your community.
For more information, visit EPA's e-Cycling website.