Use this code which is tolerant of multiple monitors:

    public class Form1 : Form
    {
        public Form1(){
            this.Load += new EventHandler(Form1_Load);
        }
       
        public void Form1_Load(object sender, EventArgs e)
        {
            MessageBox.Show("The screen resolution is: " +
Screen.FromControl(this).Bounds);
        }
    }

--
Bryan Phillips
MCSD, MCDBA, MCSE
Blog:  http://bphillips76.spaces.live.com