www.gnome.org
www.kde.org

Both sites have screenshots of their respecive desktops. I am saying this in all honesty, I find Gome to be more flexible and more powerful than any Microsoft desktop. It also offers about ten or fifteen times as many applications. How on earth can I leave it? Gnome is my favorite, although when I first started with Linux I liked KDE better. It's strange but Gnome shone through in the end.