How to call webpage from windows services in .net

using System.Net;
using System.IO; 

           string url = "http://U r Site Here";
            Uri uri = new Uri(url);
            //Create the request object
            WebRequest req = WebRequest.Create(uri);
            WebResponse resp = req.GetResponse();
            Stream stream = resp.GetResponseStream();
            StreamReader sr = new StreamReader(stream);
            string s = sr.ReadToEnd();