NPD Group reports that in just 8 months on the market, Google's Chromebooks have captured almost 25 percent of the market for laptops that cost less then $300.
It's a little difficult to know how to properly segment this kind of market, but I think the best thing to do is to take a fairly comprehensive view and just reach the conclusion that Windows is in a lot of trouble. What you often hear is that the "PC market" has started shrinking but people are buying a lot of "tablets." I think a better way to look at it, though, is that the overall market for Windows-powered devices (including tablets) is shrinking while Macs are flat and and iPad sales of surged. Android-powered tablets haven't done as well as iPads, but they're definitely growing. And now with the Chromebooks we see that another Google offering is also growing. Windows is still very strong with its clear dominance of the corporate market, but it's basically losing ground on all sides—it isn't just that the traditional PC form factor is losing appeal, Chromebook is showing some success with a different implementation of the traditional keyboard device.