Autocad is the oldest and best known CAD package that runs on a personal computer. Autocad is so commonly found in industry that many other CAD programs can read and sometimes write Autocad drawing formats. DXF (Drawing Exchange Format) is an Autocad developed files export form that is widely supported by vendors. Wikipedia has a good overview of it that's worth a quick read if your unfamiliar.
Any person working in manufacturing, architecture and design should at least be familer with Autocad.
At Smith, there are 26 seats of Autocad. It is available in any science center classroom.
You launch AutoCAD from: Start-->Programs-->AutoDesk-->AutoCad 2009-->AutoCad 2009
Some Useful Docs