string Computername = System.Windows.Forms.SystemInformation.ComputerName.ToString();

var wmiQuery = new ObjectQuery( "SELECT * FROM Win32_ComputerSystem" );

var managementObjectSearcher = new ManagementObjectSearcher( wmiQuery );

foreach ( ManagementObject m in managementObjectSearcher.Get() )
{
 Console.WriteLine( m.GetPropertyValue( "Name" ) );
 Console.WriteLine( m.GetPropertyValue( "Domain" ) );
 Console.WriteLine( m.GetPropertyValue( "DNSHostName" ) );
 Console.WriteLine( m.GetPropertyValue( "Description" ) );
 Console.WriteLine( m.GetPropertyValue( "DomainRole" ) );
}

Environment.GetEnvironmentVariable("COMPUTERNAME")