Minecraft Login

string strUsername, strPassword, strSource;
            strUsername = txtUsername.Text;
            strPassword = txtPassword.Text;

            WebClient wClient = new WebClient();

            if ((strUsername != String.Empty) && (strUsername != String.Empty))
            {
                strSource = wClient.DownloadString("http://login.minecraft.net/?user=" + strUsername + "&password=" + strPassword + "&version=13");
                string[] splitUsername = new String[] { ":" };
                string[] newSource = strSource.Split(splitUsername, StringSplitOptions.None);

                if (newSource[2] == strUsername)
                {
                    MessageBox.Show("Login Successfully!");
                }
                else
                {
                    MessageBox.Show("Bad Login!");
                }
            }
            else
            {
                MessageBox.Show("Please fill out these two textboxes first.");
                Application.Exit();
            }