Old computer and other electronic parts are a controversial topic as they're very much toxic waste if they are just thrown away (and there are beginning to be laws about how to dispose of them):

http://www.salon.com/news/feature/2006/04/10/ewaste/#

If you're not sure where you can recycle old electronic stuff safely, here's a site (U.S.) where you can type in your ZIP Code and find a responsible recyling place local to you:

http://www.electronicsrecycling.org/index.aspx