An effective way to explain something is to use a metaphor. This can be especially effective by picking an metaphorical object or behavior with which the audience is already familiar.
The one I see most often is comparing computers to a car. This morning I saw this on an email list describing a person’s experience migrating to Vista 8 from Vista 3.
It is like I have traded in a familiar (though frustrating) car for one that has the lights, wipers, and radio in new locations.
Also this morning, Vista 8 was compared to a malfunctioning pen forced on faculty who would rather use a better pen. Nevermind all pens are not used exactly the same. (Fountain vs rollerball) Some require more maintenance and care than others.
A coworker always says Free Open Source Software like Sakai or Moodle are free as in free puppies not free beer. Nevermind proprietary bought systems like Blackboard are bought as in bought puppies.