Thanks for links. I'll need some time to digest them.
ITX is too small as I need room for a TV tuner card that I already have and would like the option of adding a dedicated video card if the need arises.
I'd like to keep the cost as low as possible while keeping flexibility high. I tend to repurpose my machines somewhat frequently. I don't really have any use for a high-efficiency, low processing power machine.
Seems like my options are:
-low power "netbook" class (ITX form-factor, limited usage scenarios)
-ultra efficient PC class (relatively pricey)
-mainstream PC class (cheap CPUs but lower efficiency)
Or... buy a cheap 775 board
and move my E6400 and 8800GT to it and then replace my main machine.