Last month, John and I had a hard time trying to find a way to measure the power consumption of the VIA pc3500 motherboard. The board is designed with ultra-low power consumption in mind and we wanted to see just how well it compared to a mid-range PC. We ended up using a commercial product that is readily available in the US called a Killowatt meter, which you plug in between the device you want to test and the powerpoint. TheGreenLounge.org have produced an article and a video that explain how you can measure the power draw of devices with nothing more than a bit of math and a stop-watch. It may not be 100% accurate, but it would give you a ballpark idea on the cost of a device.