Royle
Just installed debian with a desktop manager, don't want xdm starting.
I just installed debian, with a few other things including icewm. When I boot up I go directly to xdm. I don't want to go there, I want to boot up to a console and use startx. What do I have to change? Thanks in advance for your help.

leonscape
apt-get remove --purge xdm

Will solve your problems straight away. It will be removed from all run levels, and can't return.

makuyl
You could edit /etc/inittab and set default runlevel to 3 with:
# The default runlevel.
id:3:initdefault:

Then do: update-rc.d -f xdm remove
update-rc.d xdm start 99 5 . stop 01 0 1 2 3 4 6 .

That way your computer boots to runlevel 3 with console login and you can change to xdm with: init 5