Turn off your office computer

I was appalled to realise that I am (was) one of the 1.7 million people in the UK who fail to turn off their computer before leaving work each night. Again, an article from the Independent brought to my attention by M.

I consider myself to be a reasonably ethical minded and conscientious person. We turn off lights (with energy saving bulbs), we don't keep the TV on standby, even though this means a chilly dash to the other side of the room before putting out the bedside lamp after watching a late night film. Our fridge is A grade efficient, we recycle, buy local and avoid excess packaging. But if my computer at work has been on continuously for the best part of a year, have my other efforts simply been in vain?