Vampire power is energy that is used even when hte equipment is turned off. Grinningplanet thinks that its about 10 percent of of a typical household or business use. That can really add up, for having little led's blinking all night long for the mice to eat crumbs by.
Use Kill a Watt for testing for vampire power. Computers vampire away only a few watts, but stereos, tv sets? Jeepers.