While Mxxxx implies that he has never heard of "minor" distributions like Linux Mint, Mint is the second-most common version of Linux today. Being based on Ubuntu, it has a wide range of downloadable applications. Ubuntu books can offer some background for Mint, and there is a 50-page downloadable "Getting Started" PDF for Mint. I'll post the exact title when I return home. To my mind, Ubuntu suffers from the MS disease, drastically changing the human interface just to be changing it, not to be friendlier, etc.
While I haven't tried it, Red Hat makes good money supporting a commercial version of Linux. Their free version is Fedora.