Looking in a bit more detail at the specification of the GreenPC 940 BE, the CPU is rated at 45W, which is about 20W less than the standard AMD CPUs, though interestingly is the same as standard Intel Core 2 Duos. The chip has 512KB of L2 cache per core, runs at 1900MHz (1.9GHz) and, apart from the low voltage it runs at it is basically identical to the standard AMD desktop parts. The key point to note, though, is that it is dual-core so even though it may not do one task particularly fast, it will allow you to do several things at once without grinding to a halt.
Memory comes courtesy a single 1GB stick of PC4300 DDR2. Upon initial usage I thought this was enough to get by but it quickly became clear that this wasn't the case, especially as the onboard graphics chipset takes a portion of it. The problem stems from the fact that, as memory runs out, the system needs to use the pagefile to allow programs to continue running but with a slow laptop hard drive this becomes unbearably slow. Adding in an extra 512MB sorted this out for the most part but I'd recommend going for 2GB if you plan to do anything more than browsing the web and writing Word documents, especially if you plan to add a TV tuner and use this as a low power HTPC. Either that or, rather than fork out for some extra RAM, you might be better served by opting for Windows XP Home as it is less memory hungry.
The GPU is incorporated into the motherboard, which is based on the AMD 690G chipset, and as such the 940 BE isn't a gaming powerhouse. It'll play all current DirectX 9 games but at very low resolutions and detail, stuff like The Sims and World Of Warcraft should be fine though.
To test power consumption we plugged the PC into the mains through our power monitor and manually recorded the power draw. Two measurements were taken, one with the PC idle and another with it running Prime95 and 3DMark06. For comparison we used a test bed based on an MSI K9AGM2-FIH motherboard, which uses the same chipset as the GreenPC. We popped in a typical desktop CPU - the AMD Athlon64 X2 5000+ and a 1GB stick of OCZ memory running at PC9200 speed, and added a 400GB Seagate Barracuda desktop hard drive and standard CD/DVD drive to make a full system. To show the difference that a high power graphics card makes, we also added in an 8800 GTS 320MB and ran the tests again with this as well.