Use the following script to know about the Windows Group in SQL Server
DECLARE @LoginName sysname
DECLARE @sql NVARCHAR (2000)
BEGIN
DECLARE cur_Loginfetch CURSOR FOR
SELECT [name] FROM master.sys.server_principals WHERE TYPE = 'G'
OPEN cur_Loginfetch
FETCH NEXT FROM cur_Loginfetch INTO @LoginName
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC xp_logininfo @LoginName , 'members'
FETCH NEXT FROM cur_Loginfetch INTO @LoginName
END
CLOSE cur_Loginfetch
DEALLOCATE cur_Loginfetch
RETURN
END
Sanz