I use different OS's everyday on lots of different computers. On a regular basis i use the following: Snow Leopard, Leopard, Ubuntu, Winuae, Windows 7 and xp so that's 6 different OS's. Next week sometime i will also be using MOS. But my main is Ubuntu which i use about 85% of the time. In my opinion Ubuntu is so easy to move around the place and everything else is just clumsy compared to it.