I run Ubuntu and I use it as my main OS. However, I accept that it is not Windows and never will be. I also accept that OpenOffice is not Microsoft Office. "Average Joe" user will not understand or accept these differences. Don't get me wrong, I am 100% pro Linux and Open Source but I do not think it is there on the desktop just yet. It's getting there, but it isn't there yet.
"Average Joe" won't understand having to search around for applications that are like but not quite the same as what they know and love. Gimp is great, but it is not Photoshop, for example. Ubuntu is not as "install and go" as us techy types might like to think. If something goes wrong with an install I can google for answers or pull up a command prompt as easily as brushing my hair but Average Joe won't be comfortable with this.
Finally, when you consider the Wife Acceptance Factor, you'll stick with Windows
