It's what Microsoft was lamely trying to make Windows XP look like.
I've seen some Linux screenshots and was actually impressed, especially by the 'image editor' named, oddly, GIMP
OS X is not Linux. It is an advanced user interface sitting on top of BSD Unix. You may be able to recompile GIMP for it though, I'm not sure.
I was sort of comparing all 3 of the O/S's....