NT Style groups

[Con Harte]

Hi.

I am attempting to replace a Windows NT domain, (an old
Small Business Server version) with a Linux Samba PDC.

I have set up the Samba server, and a few users, most of
which use W95 clients, and a couple of NT machine accounts.

I have not been very successful in finding out how to set up
and maintain user groups...

If anyone can help me out, or just point me in the right
direction that would be great.

Also, I am wondering if it's possible and a good idea to set up
multiple NT domains using one Samba server. (Would you need a
physical interface per domain and multiple instances of smbd/nmbd
with different config files and listening on specific interfaces?)
The priority is the groups thing though.

Thanks in advance,

Con.