Starting X without a Gnome session

[Balazs Javor <jb3@freemail.hu>]

Hi,

I'm trying to figure out the proper Debian way of chosing between
different types of X sessions.

Basically, I'm looking for the right and hopefully easy way to
experiment with X running Gnome or KDE or just some window manger.

I've been going through various X related documentation and howtos
for a long time, but they all seem to focus on various other things.
Is there some good guide related to this somewhere?

I've read somewhere that gdm would provide something like this, but
I would like to avoid using gdm or xdm etc. for now and just want to
use startx.

Also I've tried to wade through the varoius Xsession.d scripts to
find out if this is hidden there somewhere, but all I could decipher
was that it looks for the existense of /usr/bin/x-session-manager,
which in turn points to /etc/alternatives. But short of removing
the link I don't know how to disable it.
Also as said above, I want to keep somehow the possibility 
to have select each time I start X whether to run a gnome session,
or a KDE session or a particular window manager...

Any help would be greatly appreciated!
Many thanks in advance!

best regards,
Balazs