private void WebBrowser_BeforeNavigate2(object pDisp, ref object URL, ref object Flags, ref object TargetFrameName, ref object PostData, ref object Headers, ref bool Cancel) 
        { 
            string postDataText = System.Text.Encoding.ASCII.GetString(PostData as byte[]);
            this.textBox2.Text = postDataText;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            SHDocVw.WebBrowser wb = (SHDocVw.WebBrowser)webBrowser1.ActiveXInstance;
            wb.BeforeNavigate2 += new SHDocVw.DWebBrowserEvents2_BeforeNavigate2EventHandler(WebBrowser_BeforeNavigate2);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.webBrowser1.Navigate(this.textBox1.Text.Trim());
        }