How to see how many thread is working to complete my task TPL?

suppose i want to download multiple files with task parallel library and now i want to visualize how many threads are working at the time of debugging from VS2010 IDE ? here is one code snippet which download many files using TPL.

var list = new[] 
{ 
    "http://google.com", 
    "http://yahoo.com", 
    "http://ift.tt/1npNc58; 
}; 

var tasks = Parallel.ForEach(list,
        s =>
        {
            using (var client = new WebClient())
            {
                Console.WriteLine("starting to download {0}", s);
                string result = client.DownloadString((string)s);
                Console.WriteLine("finished downloading {0}", s);
            }
        });

is there any visualizer exist in VS2010 or 2012?

please guide me or redirect me to any article from where i can acquire the knowledge to see how many thread is running to complete my task.