I need to perform some action in wordpress admin panel programmatically but can't manage how to login to Wordpress using C# and HttpWebRequest.

Here is what I do:

private void button1_Click(object sender, EventArgs e)
        {
            string url = "http://localhost/wordpress/wp-login.php";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            CookieContainer cookies = new CookieContainer();

            SetupRequest(url, request, cookies);
            //request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
            //request.Headers["Accept-Language"] = "uk,ru;q=0.8,en-us;q=0.5,en;q=0.3";
            //request.Headers["Accept-Encoding"] = "gzip,deflate";
            //request.Headers["Accept-Charset"] = "windows-1251,utf-8;q=0.7,*;q=0.7";


            string user = "test";
            string pwd = "test";

            request.Credentials = new NetworkCredential(user, pwd);

            string data = string.Format(
                "log={0}&pwd={1}&wp-submit={2}&testcookie=1&redirect_to={3}",
                user, pwd, 
                System.Web.HttpUtility.UrlEncode("Log In"),
                System.Web.HttpUtility.UrlEncode("http://localhost/wordpress/wp-admin/"));

            SetRequestData(request, data);

            ShowResponse(request);
}

private static void SetupRequest(string url, HttpWebRequest request, CookieContainer cookies)
        {
            request.CookieContainer = cookies;
            request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 6.0; uk; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2 (.NET CLR 3.5.30729)";
            request.KeepAlive = true;
            request.Timeout = 120000;
            request.Method = "POST";
            request.Referer = url;
            request.ContentType = "application/x-www-form-urlencoded";
        }

        private void ShowResponse(HttpWebRequest request)
        {
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            responseTextBox.Text = (((HttpWebResponse)response).StatusDescription);
            responseTextBox.Text += "\r\n";
            StreamReader reader = new StreamReader(response.GetResponseStream());
            responseTextBox.Text += reader.ReadToEnd();
        }

        private static void SetRequestData(HttpWebRequest request, string data)
        {
            byte[] streamData = Encoding.ASCII.GetBytes(data);
            request.ContentLength = streamData.Length;

            Stream dataStream = request.GetRequestStream();
            dataStream.Write(streamData, 0, streamData.Length);
            dataStream.Close();
        }

But unfortunately in responce I get only HTML source code of login page and it seems that cookies don't contain session ID. All requests which I perform after that code also return HTML source of login page so I can assume that it does not login correctly.

Can anybody help me to solve that problem or give working example?

Main thing which I want to achieve is scanning for new images in Nextgen Gallery plugin for Wordpress. Is there XML-RPC way of doing that?

Thanks in advance.