public void ScrollingLabel(Label l) {
			for (int i = l.Location.X; i >= 0; i--) {
				l.Location = new Point(l.Location.X-1, l.Location.Y);
				System.Threading.Thread.Sleep(50);
			}
		}

public delegate void ScrollTextboxCallback(string t);
string marqueeText = "This is only a test.";

Thread thread = new Thread(new ThreadStart(ScrollTextbox));
thread.Start();

private void ScrollTextBox()
{
      string tempChar = string.Empty;
      string tempText = string.Empty;
      tempText = marqueeText + "      ";  // adds spaces at the end of the text so there is a clear ending to the text
    
      while (true)
      {
             tempChar = tempText.SubString(0,1);
             tempText = tempText.Remove(0,1) + tempChar;
             textBox1.Invoke(new ScrollTextboxCallback(this.UpdateTextBox), new object[] { tempText });
             Thread.Sleep(100);  //lowering this value with make the marquee scroll faster
      }
}

private void UpdateTextBox(string m_text)
{
     textBox1.Text = m_text;
}