Technicians go to to the command line interface of XP all the time to, for instance, configure network settings. In addition, although I'm no Linux guru, I've used distributions that didn't require using the command line for the tasks I was interested in doing, Linspire comes to mind.
And although Free BSD isn't Linux, it is a UNIX look-alike, and Apple has chosen it to under gird their standard OS. So more people are using open source than realize it.
Linix may never have the market share Windows does, but the ease of use keeps increasing and the debate seems to have degraded into a mere debate over preference rather than capability.
I just installed OpenSolaris on my ThinkPad. No command line necessary. It installed with a few mouse clicks and found my wireless network automatically. Its the first Linux I’ve use thats really good for something. Try it at http://www.opensolaris.com.
I won a Mac laptop in a lottery at work around Christmas (Sorry! around "Holiday".)
At first I didn't care for it much. The e-mail client was OK but Safari was not Firefox, or even IE. Upgrading it to Leopard was fun but I didn't really get into it until I discovered I could get to the command interpreter. There's a real operating system in there!