Let me ask you a basic question: Which operating system do you use? What are the possible answers? Windows, Linux, Solaris or Mac OS X of course. But let us try to think different for a moment. Maybe it is possible, that this answer would be, for example KDE?
Let me get this straight — this idea seems a little bit odd at the first glance. Everybody knows that KDE is a graphical environment just like GNOME, Aqua or Aero are. Graphical environment, and that means only a part of an operating system. But the the fact is that 99.9 percent of users are interested only in this small part. Maybe you’ll say that this is just beating the bush, but I seriously think that what counts for an average user is not an operating system but rather an environment they use to work with. A graphical environment of course.
Please take a quick look at a picture below. It shows well known (and liked) GNOME desktop. What’s more, for a more experienced user it’ll look a little bit familiar — namely just like Ubuntu. Just like… because there’s only one little problem — it is not Ubuntu GNU/Linux. Especially it is not Linux at all. It is Nexenta GNU/OpenSolaris.
More Here