How to change from KDM to GDM?

[KiwiLinux7.10]

Hi people , well i just add three users to my Desktop Linux ,and i am the administrator of my brother ,and my two cousins and that's great.

But to have a full great OS i installed KDE 4.0 in Ubuntu 8.04 and at the configuration i didn't know and i choose KDM to be my default but i want badly to be GDM my default cause i am really used to it , the SWITCH USER option work much better there so can anyone tell me how to do that ? I tried from GNOME but it stopped me saying that it was not running GDM . I tried from KDE ,but i cannot find how to do it .

Please help!

Okay i found my way around Switch user in KDE to work perfect ,but tell me anyway how to change , i like learning

[devils casper]

Execute this

sudo dpkg-reconfigure kdm

Select kdm in the list.

[KiwiLinux7.10]

I used this command to get this error
Package `kdm' is not installed and no info is available.
Use dpkg --info (= dpkg-deb --info) to examine archive files,
and dpkg --contents (= dpkg-deb --contents) to list their contents.
/usr/sbin/dpkg-reconfigure: kdm is not installed
kejdi@kejdi-desktop:~$
then i followed the same command with GDM instead of KDm and i selected it from the list.

Many thanks man.