How do i change my login manager?
This is got to be one of those newbie questions
that drives people nutz.

Pretty simple. Open the file /etc/X11/default-display-manager with your editor of choice. Make sure you invoke that editor as root, otherwise it won't work. In that file there's a single line: /usr/bin/kdm Change that to /usr/bin/gdm and save the file. Reboot and you're in Gnome.

Thanks that was simple.
One more thing I want to change the gdm screen to one
i got from gnomelook but when i do:
Desktop>Administration>Login Window
I get a screen displaying that i been granted root access, so i click
'close' but then no Login Window, it dosn't run.
Tried running from a terminal but i get 'Login commd not found'
Is the Xserver rejecting my call to the program?
or is it a bug?

Logout of your xsession. This will take you back to the GDM login screen. Click on "Actions" and choose "Configure Login Manager". You can then install the new GDM theme and configure it.

in SuSE you have to edit two files:
/etc/sysconfig/windowmanager
/etc/sysconfig/displaymanager

ref: http://www.novell.com/coolsolutions/feature/15333.html

I'm sure it is, but:
a) this is the Debian forum
b) this thread is 9 months old

Do you really think that info would be usefull here? I know it doesn't... :-\

I guess you didn't find this thread as a number one google search like I did.

while we're here again, I think I'll go ahead and mention this super easy super fast way of switching from KDM to GDM by default.

First you need to know if you have both installed. If not, install the one you don't have.

sudo apt-get install gdm to install GDM.

sudo apt-get install kdm to install KDM.

If you already have both installed then reconfigure one of them (it doesn't matter which one) like so:

sudo dpkg-reconfigure gdm

Now, it doesn't matter which of the three above mentioned methods you used, you will be presented with a dialog asking you which default you want to have (if, and only if, you have successfully installed more than one). Make your choice.

Simple.