According to the Chinese PC maker the BlueSky PCs only use 45W (without the display). The basic system features a Sempron LE1150 CPU, 512MB memory, 80GB HDD, Radeon X1200 graphics, DVD player and a power supply with a 85% efficiency.
The cheapest configuration with a Sempron processor costs only $399. A system with the Athlon 64 X2 BE2350 processor, 1GB memory and 160GB HDD costs $649.
One of the other things that sets this PC apart from the crowd is that Lenovo can ship it with a solar panel that generates enough electricity to power the system but it's not clear how much this will cost - I guess it's probably at least triple the cost of the cheapest system.