Good points. I try to do the same and am in fact staying over in Birmingham tomorrow to save on the unessesary milage over two days. I also like to use my laptop on the battery where possible so as not to be contantly drawing on the mains. I am sure switching between uses less power.

I recently bought one of these devices as well.. http://www.reuk.co.uk/Owl-Wireless-Electricity-Monitor.htm It is amazing seeing what is being used and when..