Someone

static void Main(string[] args)
        {
            String path = "c:\\";
            string[] files;

            files = Directory.GetDirectories(path);
            for (int i = 0; i < files.Length; i++)
            {
                Console.Out.WriteLine(" => " + files[i]);
                string[] dirs = Directory.GetDirectories(files[i]);
                for (int j = 0; j < dirs.Length; j++)
                    Console.Out.WriteLine("\t=> " + dirs[j]);
            }

            Console.In.ReadLine();
        }