A program called cygwin let's you run Linux at the same time as Windows and there is a version called Knoppix that can be run off a bootable CD.
But for non-technically minded people, who don't necessarily like using computers much, Linux is still less user-friendly than Windows or the Mac. Linux is more configurable though. You see computer-knowledgable people prefer it that way and wouldn't sacrifice configurability for ease-of-use and usability.
