Получить HTML код страницы

    static string getResponse(string uri)
    {
        StringBuilder sb = new StringBuilder();
        byte[] buf = new byte[8192];
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream resStream = response.GetResponseStream();        
        int count = 0;
        do
        {
            count = resStream.Read(buf, 0, buf.Length);
            if (count != 0)
            {                
                sb.Append(Encoding.Default.GetString(buf, 0, count));
            }
        }
        while (count > 0);
        return sb.ToString();
    }

String MyURI = "http://www.contoso.com/";
WebRequest WReq = WebRequest.Create (MyURI);
WReq.Credentials = CredentialCache.DefaultCredentials;

String MyURI = "http://www.contoso.com/";
WebRequest WReq = WebRequest.Create (MyURI);
WReq.Credentials = 
    new NetworkCredential(UserName, SecurelyStoredPassword, Domain);

var webClient = new System.Net.WebClient();
webClient.Credentials = new System.Net.NetworkCredential("login", "password");
string HTML = webClient.DownloadString("http://sitename.ru");

static string getResponse(string uri)
    {
        StringBuilder sb = new StringBuilder();
        byte[] buf = new byte[8192];
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream resStream = response.GetResponseStream();        
        int count = 0;
        do
        {
            count = resStream.Read(buf, 0, buf.Length);
            if (count != 0)
            {                
                sb.Append(Encoding.Default.GetString(buf, 0, count));
            }
        }
        while (count > 0);
        return sb.ToString();
    }

static string getResponse(string uri)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.UserAgent = "My applicartion name";
    using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.Default, true, 8192))
    {
        return reader.ReadToEnd();
    }
}