A little hint, if your HDDs aren't hibernating in XPEnology, turn off "Hot Swap" support in the PC BIOS. Hot swap polls the drives too often, stopping them from hibernating.
I'm a sucker for new and shiny things, so I ordered an AsRock AD2550R/U3S3 Server Board (Atom D2550, Intel ICH10R, DDR3, S-ATA 600, Mini ITX) - 10W processor, and 7 SATA connectors on the board. As my LSI HBA is using about 7W on it's own, I'm thinking I should be able to save 10W of power at the wall by getting rid of it and using a board with sufficient SATA connectors. Also with dual Intel NICs on board I should be able to bind them for 2Gb connectivity. I'm starting to think I might need to go to a Pico PSU...I'm getting well below the point where even the 250W 1U PSU in the Norco will be well outside it's most efficient loading.