Following up on this, just in case anyone is interested in FreeBSD 7...
The problem with Xorg doing a core dump upon exiting any session is
directly traced to using KDM.
If I switch to xdm, and simply put a one line .xsession file in my local
directory containing the single word: startkde
it works fine. No more xorg crash on logout.
I don't get the fancy session switching capability
of the kdm login screen but its good enough.
The integration of kde and freebsd seems flawless, and when attached to
a windows network the network browsing works better than either my suse 10.3
or my ubuntu virtual machines.