{Replying to Daniel Jitnah <djitnah@greenwareit.com.au>:]
FWIW, I have no doubt in my mind that the heat from the 400W power supply in my PC is contributing to heating my house! The room where this PC is located is distinctly slightly warmer than the rest of the house and there is no other obvious reason for this to be so. In fact, this room should be cooler as is one of the rooms further away from the ducted heating unit, but it is not.
Going in the other direction, towards lower power use: In fact that's one of the reasons why I switched from a regular PC tower (at 140W) to a Fit-PC (2W idle, 8W at full tilt) for my home server. I figured it would pay for itself in a couple of years of power bills savings. Those little Android dongles, like the RK808, sometimes styled "Google TV" are pretty cheap (around $50 these days) and would make that trade-off even more attractive -- though it depends on what your needs are. There are efforts going on to run say Debian natively on such devices (rather than in say a chroot). I use my Raspberry Pi often as a low-end desktop machine and it's mostly usable for simple things -- if a bit laggy at times. I wonder how much faster it would run off an external USB drive instead of the SD card. I suspect that swap is the main laggy factor. -- Smiles, Les.