So here is something really cool I just discovered.  I decided to install the Mac version of Steam, so I could look at some downloadable games.  When I got it installed, I logged-in with the Steam account I made nearly 6 years ago when I first bought Half-Life 2 for my PC.    When I logged-in, I found out that the  Mac version was available for me to download…for free!   Now that is cool.  The honored my license, even after I moved to a new OS.  Valve rules!