How to switch graphical environment

[M.D.]

Hi,
I use mandrake linux, and i work in KDE.
Wanted to work on ctwm,
downloaded and installed the rpm file.

But it won't load.
I went to cntrol center, and added it in the lilo options.
Then i went to gdm directory, and added ctwm file to the Sessions directory inside. (as there is for IceWm, KDE and other graphical ****)

But still it won;t work, when i pick ctwm in the login scree, it loads me IceWm!!!!

Some one knows how can I make it work?

are they the same or different?i never heard of ctwm
is it the same or close to icewm
, kevin