It will make some power usage savings by using the case as a heatsink, avoiding the need for case fans. The power supply will also be external as on a laptop, to help keep the components cool. PC World claim that it will only use 40W, which is less than a fifth of the average desktop. They also claim that they haven't traded performance for efficiency, and that the machine will be as well featured as comparably priced computers. A price of £399 ($800) is expected, although the screen will cost an extra £100 ($200).
Peter Lyons, from PC World's parent company, was quoted in the Independent article, "In the past, environmental products have asked consumers to make a compromise. That's why they haven't been very successful -- previous low-power units have performed very slowly so they can't do as much as a standard computer. But this is going to have the same sort of power as one of the average units on sale at Christmas -- and it will cost about the same, too."
One detail that may surprise people is that it will come pre-installed with Windows Vista. Previous energy-saving PCs have sometimes come installed with some variation of Linux, because it is less power-hungry and can run on lower-power machines. However, if PC World are right in claiming that they haven't skimped on power, then this shouldn't be a problem. Also, if they want this machine to be desirable to mainstream customers, then Linux could be slightly off-putting. It would be a shame to have a green PC on the market that doesn't sell well because people are scared of using Linux. Of course, if I had my way, all PCs would be green and all computers would run Linux or OS X. ::CNet