x windows system is the GUI environment for unix/linux, correct? and KDE/gnome/etc is kind of like a layer around x windows, almost like a sophisticated skin, correct? if so, how come unix can't use all the different environments like KDE, or if it can, why is linux always considered to be the more friendly OS due to its windows-like GUI? I know im wrong somewhere here in my assumptions, so can someone just straighten me out? 
