Load of tosh
To the bog standard computer user Linux is too difficult...simple as, and until this changes there will never be a massive uptake.
All my PC's run windows, can't say they ever crash and nor have I ever got a virus, and I never get spyware either.....I look after my PC.
I've tried Linux, but as a web developer I missed photoshop and dreamweaver, and then visual studio and the .net framework....yeh there's wine, but it's such a pain to setup.
Windows seems to be a common platform, if someone gives me a file or application, it's likely it'll come from a windows machine, simply because there are more windows machines around than Linux machines, and if I wanted to get half the stuff I was given to work on linux it would involve re-compliling the kernel and looking for dependencies or something like that.....which is a really time consuming task.
I'm not bashing linux, there's a lot of effort going into building each distro, but the facts are plain to see, it's not as easy to use as windows, and getting stuff to work can be too difficult or time consuming for people with busy lives.