httpwebrequest 抓取网页数据返回的是application/vnd.ms-excel格式应该怎么处理？

下面是我的代码HttpWebRequest request = null;
            Stream rspStm = null;
            //创建Request对象
            try
            {
                request = (HttpWebRequest)HttpWebRequest.Create(requestUrl);
                request.ContentType = "application/vnd.ms-excel";      //给ContentType赋值
                request.CookieContainer = cc;           //保存cookie
                request.Method = "GET";                 //提交的方法
                request.Referer = "http://beidou.baidu.com/index.html#/";              //设置标头的值
                request.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E)";
                request.KeepAlive = true;
                request.Accept = "image/jpeg, image/gif, image/pjpeg, application/x-ms-application, application/xaml+xml, application/x-ms-xbap, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                cc.Add(response.Cookies);                rspStm = response.GetResponseStream();                StreamReader reader = new StreamReader(rspStm, Encoding.UTF8);                string html = reader.ReadToEnd();            }
            catch (Exception)
            {                throw;
            }
            finally
            {
                rspStm.Close();
                request.Abort();
            }但是我提供的网址在Ie输入直接是一个下载页面，抓包抓取出来的数值如下：
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=270CAEAD442F9B0690D86A036FA3E402; Path=/report
Content-Disposition: attachment;filename="东方海洋-账户分日报告-20120605-20120605.csv"
Content-Type: application/vnd.ms-excel
Content-Language: zh-CN
Content-Length: 239
Date: Wed, 06 Jun 2012 02:31:13 GMT
Connection: close日期,展现次数,点击次数,点击率,平均点击价格(元),千次展现成本(元),总费用(元)
2012-06-05,22240,17,0.0764%,0.97,0.74,16.42
合计：,22240,17,0.0764%,0.97,0.74,16.42这是Stream中的返回值，但是我用上面的程序，一直抓取不到他的内容，求高手指教！不胜感激！