how many distributions for linux / windows?
Sorry to get you stirred up. Unix has been around for a long time. Linux was, to my knowledge, the first unix based end-user OS. When Linux started to get popular in the late 90's I had so many problems getting it up and running that I put it aside no less than six times so as to ensure my machine was not tossed out of a third story window. Back then I was ecstatic to get X Server up, not to mention having a sound card!
Yes, there is only one Kernel, but how many distributions have been made? Can you imagine what our community could accomplish if we focused on only, heck lets say 20!
As far as how user friendly windows has become. Unless you are modifying the windows registry, installation, maintenance, and troubleshooting are straight forward with plenty of documentation. Granted it helps having hardware manufactures assisting with the development of your drivers/software, but if we pressured them more I'm sure we could have the same thing. Look how things have already changed in the last three years.
Again sorry to stir the pot here, you did point him in the right direction.