private void IconToBitmap(PaintEventArgs e)
{
    // Construct an Icon.
    Icon icon1 = new Icon(SystemIcons.Exclamation, 40, 40);

    // Call ToBitmap to convert it.
    Bitmap bmp = icon1.ToBitmap();

    // Draw the bitmap.
    e.Graphics.DrawImage(bmp, new Point(30, 30));
}

/*
Professional Windows GUI Programming Using C#
by Jay Glynn, Csaba Torok, Richard Conway, Wahid Choudhury, 
   Zach Greenvoss, Shripad Kulkarni, Neil Whitlow

Publisher: Peer Information
ISBN: 1861007663
*/
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

using System.Net;
using System.IO;

namespace ImageIcon
{
    /// <summary>
    /// Summary description for ImageIconForm.
    /// </summary>
    public class ImageIconForm : System.Windows.Forms.Form
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components = null;

        public ImageIconForm()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();

            //
            // TODO: Add any constructor code after InitializeComponent call
            //
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null) 
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            // 
            // ImageIconForm
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(292, 266);
            this.Name = "ImageIconForm";
            this.Text = "ImageIconForm";
        }
        #endregion

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main() 
        {
            Application.Run(new ImageIconForm());
        }
        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {
            // Icon 3 times:
            string p = @"C:\Program Files\Microsoft Visual Studio .NET\VC#\CSharpProjectItems\icon.ico";
            Icon ic = new Icon(p);
            this.Icon = ic;  // Icon 1)
            Graphics g = e.Graphics;
            g.DrawIcon(ic, 0, 0);  // Icon 2)
            Image i = ic.ToBitmap();
            g.DrawImage(i, 50, 0);  // Icon 3)

            // Thumbnail:
            p = @"MonetZsu.JPG";
            i = Image.FromFile(p);
            Image tn = i.GetThumbnailImage(50, 50, null, IntPtr.Zero);  // <=>(IntPtr)0
            g.DrawImage(tn, 100, 0, tn.Width, tn.Height);

            // Picture from Internet:
            p = "http://www.kosice.sk/newimg/kolazx4.jpg";
            WebRequest wReq = WebRequest.Create(p);  // using System.Net;
            WebResponse wRes = wReq.GetResponse();
            Stream strm = wRes.GetResponseStream();  // using System.IO;
            Image im = Image.FromStream(strm);
            g.DrawImage(im, 0, 50);
            strm.Close();
      
            g.Dispose();
        }
    }
}