This query should get you started. It will list all AD users not in the Domain Admins group.
Select tblADusers.Username,
tblADusers.Userdomain,
tblADusers.Firstname,
tblADusers.Lastname
From tblADusers
Where tblADusers.ADObjectID Not In (Select tblADMembership.ChildAdObjectID
From tblADMembership Inner Join tblADGroups On tblADGroups.ADObjectID =
tblADMembership.ParentAdObjectID Where tblADGroups.Name = 'Domain Admins')
Order By tblADusers.Username