@incredible, I now do all my work on a netbook running Ubuntu. At home its plugged into a monitor and mouse so I hardly notice the difference, and elsewhere it so much lighter than smaller than my laptop that it makes up for the smaller screen and keyboard.
I also agree with bakedjake that the cost of OSes is not really a factor: if I preferred Windows, I would be happy to pay for it: in fact my netbook came with Windows so I have been forced to pay for it anyway. I prefer Linux so I deleted the Windows install.
Most people will not do that, and Windows will be the dominant PC OS for the foreseeable future, BUT more and more of our usage of computers will be of non-PC devices which Windows is weak on. It is quite surprising how much you can do in the cloud if you want to (I do not like that idea, but most people do).