xorg, xdm, desktop env

[n dhert]

Installed a fresh FreeBSD-8.0, xorg, configured xorg for my screen,
installed xdm.
After reboot I see a graphical login window. When entering username and
password, it seems to accept it, but immediatly present the graphical login
window again. (In console mode (Ctrl-Alt-F1) I can login at the login:
prompt with the
same username/password).
Has FreeSBD somewhere a default environment (in that case why does it not
appear after logging in at the
XDM graphical window) or do you still need to install a Desktop environment
(Gnome, KDE, Xfce) and is it
normal that after logging in at the XDM window, you are thrown out again..