All glory goes to Kevin Niederhauser with an assist from Jeff Pickett ;
Here's what I did to get the data that I needed. the bit mask is on the groups table, column gr_group_id. It is related to the (int) column on the users table...us_group.
sa.full_name, gr_group_name from
[USERS] u, [GROUPS] g, [qcsiteadmin_db].[td].[USERS] sa
where substring(u.us_group, g.gr_group_id + 1, 1) = '1'
and u.us_username = sa.user_name
order by sa.full_name