Good advice from Techlicious on how to safely dispose of your old computer.  Steps include:

1. overwriting
2. encrypting
3. deauthorizing
4. deleting browsing history
5. uninstalling programs
6. consulting with your employer regarding data policies
7. wiping your hard drive
8. physically destroying your hard drive

With links to software that will do the job for free (or cheaply).  

Whether you’re a Windows or Mac user, operating system settings are clear and easy to follow. 

Read the full post here.  Also included are suggestions on backing up before destruction and resources on recycling or trading in your computer.