class WMIWrapper
    {
        private string m_ComputerName = string.Empty;
        private string m_UserName = string.Empty;
        private string m_Password = string.Empty;
        private ManagementScope Ms = null;
        private bool? bLocalConnect = null;

        public WMIWrapper(string computerName)
        {
            this.m_ComputerName = computerName;
            this.bLocalConnect = true;
        }

        public WMIWrapper(string computerName, string userName, string password)
        {
            this.m_ComputerName = computerName;
            this.m_UserName = userName;
            this.m_Password = password;
            this.bLocalConnect = false;
        }

        private void Connect()
        {           
            if (true == bLocalConnect)
            {
                if (null == Ms)
                {                    
                    Ms = new ManagementScope("\\\\" + m_ComputerName + "\\root\\cimv2");  
                }
            }
            else
            {
                ConnectionOptions con = new ConnectionOptions();
                con.Username = m_UserName;
                con.Password = m_Password;
                if (null == Ms)
                {
                    Ms = new ManagementScope("\\\\" + m_ComputerName + "\\root\\cimv2", con); 
                }
            }

            try
            {
                Ms.Connect();
            }
            catch (ManagementException ex )
            {               
                throw ex;
            }
        }

        public ManagementObjectCollection ExecuteQuery(string queryString)
        {
            this.Connect();
            ObjectQuery Mq = new ObjectQuery(queryString);
            ManagementObjectSearcher Mos = new ManagementObjectSearcher(Ms, Mq);
            return Mos.Get();           
        }

        public string GetValueByProperityName(string queryString,string properityName)
        {
            this.Connect();
            ObjectQuery Mq = new ObjectQuery(queryString);
            ManagementObjectSearcher Mos = new ManagementObjectSearcher(Ms, Mq);
            ManagementObjectCollection col = Mos.Get();

            string strValue = null;
            if (col.Count != 0)
            {
                foreach (ManagementObject m in col)
                {
                    strValue = m.Properties[properityName].Value.ToString();
                    break;                   
                }
            }
            return strValue;
        }
    }