Power saving via policies, Windows Update and remote access

Hi all,

I'd like to push out a power policy to the Vista machines on my network and
save some power, but at the same time I'd like them all to update out of
office hours.

It seems sleep and hibernate need a wake from LAN magic packet sent to each
machine before they will connect to WSUS as scheduled, and I don't want to
use this - so am I limited to just powering off the hard drives and monitors?

I'd like to save as much power is practical - these are office machines
rarely used out of office hours, but cannot be turned off or be unresponsive
due to regular remote access sessions.

Best regards,

Chris Mancuska