What makes a Desktop Environment?
 

it's, maybe, a lame question; but i guessed that a Desktop Environment is called that way becouse includes a Window Mangaer, a Panel, Desktop Manager, Session Manager, and some other software... The thing is that i do consider XFCE to be a Desktop Environment, but some of my friends keep telling me it isn't becouse it doesn't includes enough software ... i'd like to hear what you people have to say about this...

you're right, they're wrong

here's a textbook answer, and it even lists xfce as a desktop environment

http://en.wikipedia.org/wiki/Desktop_environment