hmm, here is my partial understanding:
x windows is what allows the graphical display on linux. so, for example, i have an x windows server on my M$ box at work so that i can ssh to my home comp and run my graphical programs.
kde is a desktop environment that has various features such as the menus, panels, etc.
sawfish is a window manager and it controls how your windows are displayed and what kind of control you have over them.
for example, gnome is the desktop environment and uses nautillus as its windows manager, but it all takes place through an x windows server (i think).
on one of my linux boxes, i use the window manager "windowmaker" and no desktop environment.
you can actually read all about this at http://www.redhat.com/docs/manuals/l...uide/ch-x.html
redhat has pretty good documentation, so you might want to search there when you run into questions.