I was 
reading this article at BBC’s (Gadget threaten energy savings) and was not really surprised about the finding that the larger the LCD screen, the more power they use, eventually, topping regular CRT screens (at and around 24 or 25 inches). This is basically because each pixel on an LCD screen requires power. With larger resolutions, LCD manufacturers use ‘multiplexing’ to power LCD screens.
I am surprised to see that projection TVs actually do good. If you want the read the whole report yourself, here you go (if that link goes dead in the future, try here: look for ‘The Ampere strikes back’ article).
Talking about LCD screens: I discovered my first dead pixel on my laptop screen.