Windows Server is an operating system where the apps running don't need much of an interface, if at all, yet it still has a full Windows desktop. That's going to change with the latest version, though. The Windows Server team has posted a lengthy blog explaining their decision to cut down the Server's desktop and make it optional. It makes sense to remove the GUI, given the amount of resources it consumes and that most management of servers is done from a remote desktop and not the actual server itself. I'm sure Unix supporters are welcoming Microsoft to 1990.