encoding formats in c#

Hi I think I did not make my self clear.
public string DownloadWebPage(string Url)
{
// Open a connection
HttpWebRequest WebRequestObject = (HttpWebRequest)HttpWebRequest.Create(Url);

// You can also specify additional header values like
// the user agent or the referer:
WebRequestObject.UserAgent = ".NET Framework/2.0";
WebRequestObject.Referer = "http://www.example.com/";

// Request response:
WebResponse Response = WebRequestObject.GetResponse();
// Open data stream:
Stream WebStream = Response.GetResponseStream();

// Create reader object:
StreamReader Reader = new StreamReader(WebStream);

// Read the entire stream content:
string PageContent = Reader.ReadToEnd();

// Cleanup
Reader.Close();
WebStream.Close();
Response.Close();

return PageContent;
}
this the code i am using to download a web page. Now if a page is in arabic language when it will be stored in a file it should be visible same what it did on site page.
For example now a page arabic is using utf-8 or utf-16 or anything else. I have to use same while writing in file.
How can I get the text in same unicode format.