switch off
I switch everything off too, except the router (but switch this off every week or so as we are on a fixed 2 Mbit connection not ADSLmax or whatever, so no BRAS profile nonsense).
Anyway, we have so many power interruptions here things need to be robust.
Only issue I get is with wife's vista laptop which is the print server. Think this is more a vista issue so I'll upgrade to W7 if I ever find my wallet.
The room with two computers in gets quite toasty, don't know what the power draw is on standby but feels like a few hundred watts of heat in total.