This is only an anecdote, but when I whip out my ubuntu laptop, people don't say 'what's that' anymore, they say 'cool ubuntu, how is it?'
Up until fairly recently you had to hack around with text files in shell in order to set up simple things like multiple monitors and proper sound support.
That sort of stuff got a lot better with version 8, and with the current version, 9.10 i'd say that using Ubuntu is as easy as using windows (possibly easier).
The only barrier currently is 'can i buy an OS disk in the store', and 'can I get a computer with it pre-installed'.