In the past, I thought I would buy a Mac Book Pro to replace my old 3 years Dell Inspiron. That time I heard "MacOS is a comprehensive Java development environment". Also in the point of view of an end user, GUI in MacOS it's more beautiful than the one in Linux and it has many more popular (and better) applications than Linux (You must know that when I used Ubuntu, even I could listen to the music, Skype's voice feature stopped to work without any errors)
But now there is no Java 6 in Leopard (MacOS X 10.5), so I quit. I think you too if you're a Java developer.