Do we really need to dump our old inefficient appliances to save money and the world?

There is a big campaign by AMDEA trying to persuade us to throw away our old inefficient appliances and buy new more efficient ones. They claim we will be helping save the earth and will save ourselves lots of money too. However, although I agree that new appliances are usually more efficient I have more difficulty in accepting that it makes sense to throw away a perfectly good white goods appliance if it is working okay in order to save either money or save the environment.