Everyone knows that Windows is installed on the vast majority of computers, but it's always interesting to be reminded of what a cash cow the OS has been for Redmond. According to Gartner, Microsoft owned 78.6 percent of the global market revenue share for desktop operating systems at the end of 2010 -- revenue up almost 9 percent from 2009. That means, of the $30.4 billion in revenue that various companies generated, $23.8 billion lined Microsoft's coffers. But while Windows remains the kingpin, Mac OS X and -- wait for it -- Red Hat, posted more substantial gains. Apple's market revenue shot up almost 16 percent to 1.7 percent, Red Hat surged 18 percent, while dark horse Oracle leaped from ninth place to fourth, with a 7,683 percent growth in income -- no small thanks to its 2009 acquisition of Sun Microsystems. Only one question remains, then -- who's the loser here?

Update: Looks like we got this one wrong, folks, as it's not market share that's being measured here, but rather revenue share -- how much money each company made from its operating systems relative to one another. That means companies that price their operating systems cheaper will be at a disadvantage in the rankings, not to mention those organizations that charge nothing at all -- Ubuntu, anyone? Oh, and as some of you have pointed out in comments, there are both desktop and server operating systems in the chart above.