I'd investigate hibernation too - you should be able to do this with Win2K.
You can set your machine to STR after a certain time, then have the machine wake and hibernate after a period of time in STR state.
Whether you can trigger the hibernate following STR without going into STR through a timeout, I don't know, but it's worth a play
Hibernate serialises your memory and state to disc, and takes zero power. All that'll be running is your +5V standby line, which draws next to bugger all.
Boot time for me from hibernated takes around 20 seconds.
Cheers,
Nick.