I don't think ChromeOS will "knock out" Windows, especially with Windows 7 coming out but I do think it will be good for Linux as a whole. It will get a lot more people interested in Linux than before since almost everyone knows knows about Google but not everybody has heard of Ubuntu,SuSe, Red Hat/Fedora, Debian, etc... See what I mean? It would be like if Microsoft marketed Linux, all the sudden people would be like "Wow look at this brand new Microsoft OS it's awesome!" when Linux has actually been around for about 15 years. All in All it's about getting the word of it out, about 80-90% of computer users probably have no idea what Linux is since it's not marketed and shoved in our faces at every turn like everything else in this world is.
[citation][nom]doomtomb[/nom]The Google Chrome OS is exactly as they put it: another iteration of Linux. While making the argument that Windows is something "different" is hard to do because it is everywhere, still, you don't see other OSs that similar to Windows, probably because it is closed source.[/citation]
I guess you've never seen
ReactOS its pretty much an open source clone of Windows XP but it's built entirely from scratch and doesn't use any Microsoft code. It's still in the Alpha stages though (0.3.10), even after a few years.