One look at this chart, and it becomes obvious why Windows and Mac OS are eventually doomed to legacy status. Apparently, more collective time has already been spent developing Linux since 1992 than all the total Microsoft and Apple man-hours combined.
Linux Distribution Timeline
It was fun to root around and find where my favorite versions belong in the mix. It's interesting to explore the distributions that were developed independent of the big three (Debian, Slackware, Red Hat).
Also interesting to note that Debian and Slackware were started a year after Torvald's first kernel was released, and Red Hat two years. Once those three took hold, the whole movement exploded with possibility.