administrator=root

and group.map looks like:
domain users:domuser

You may need to do it like
domain\ users:domuser
I'm not exactly sure anymore, read the docs. 

To use the maps, under [Global] in smb.conf:
username map = /etc/samba/username.map
group map = /etc/samba/group.map

If you're samba server is part of the NT domain you shouldn't have to worry
about the maps too much. I still have to get around to working with 2.2
however, so things may be different.

--
Andy Zbikowski, Sys Admin   | (WEB) http://www.ltiflex.com
LTI Flexible Products, Inc. | (PH)  763-428-9119 (EX) 132
21801 Industrial Blvd       | (FX)  763-428-9126
Rogers, MN  55374           | (PCS) 612-306-6055