利用XMLHTTP下载文件，和以前的方法一样，先添加引用－COM－Microsoft Xml 3.0，然后在代码开始处写：
  
  using MSXML2;
  下面就是主要的代码： 
   
   private void Page_Load(object sender, System.EventArgs e)
  {
   string Url = "http://dotnet.chinaitlab.com/UploadFiles_6597/200611/20061130113617553.gif";
   string StringFileName = Url.Substring(Url.LastIndexOf("/") + 1);
   string StringFilePath = Request.PhysicalApplicationPath;
   if(!StringFilePath.EndsWith("/")) StringFilePath += "/";
   MSXML2.XMLHTTP _xmlhttp = new MSXML2.XMLHTTPClass();
   _xmlhttp.open("GET",Url,false,null,null);
   _xmlhttp.send("");
   if( _xmlhttp.readyState == 4 )
   {
   if(System.IO.File.Exists(StringFilePath + StringFileName))
   System.IO.File.Delete(StringFilePath + StringFileName);
   System.IO.FileStream fs = new System.IO.FileStream(StringFilePath + StringFileName, System.IO.FileMode.CreateNew);
   System.IO.BinaryWriter w = new System.IO.BinaryWriter(fs);
   w.Write((byte[])_xmlhttp.responseBody);
   w.Close();
   fs.Close();
   Response.Write ("文件已经得到。<br><a href='" + Request.ApplicationPath + StringFileName +"' target='_blank'>");
   Response.Write ("查看" + StringFileName + "</a>");
   }
   else
   Response.Write (_xmlhttp.statusText);
   Response.End();