Get a synology NAS, I have one and they are brilliant! You can schedule it to turn off and back on for whenever you want. Mine turns off at 2 then comes back on at 8am. There's an app as well so you can quickly turn it off at any time. I haven't got around to setting up wake on LAN but its possible.
Great UI and a ton of apps to access your music, photos, docs etc from outside the house..
Thanks for the info. I'll check what SOHO NAS are available that can be woken up through WOL.
I also have to build a new, completely silent Windows workstation that can really be put to sleep, including the CPU and PSU, and still be able to wake up in the middle of the night for SyncBackSE to run, wake up the NAS, do its thing, and have both devices go back to sleep.
That should save a bit of power.
Hopefully, full sleep mode is hardware-based so I can just move the XPSP3 disk to the new workstation instead of migrating to Windows7.