如何在Silverlight中编写每10秒执行一次的程序

如何在Silverlight中编写程序，每10秒做一些事情，例如，处理twitter搜索结果?最接近的是:

        // Get and process new twitter search results evey 10 seconds
        BackgroundWorker worker = new BackgroundWorker();
        worker.DoWork += (sender, args) =>
        {
            while (true)
            {
                //Get results of Twitter Search and process them in the above code
                client.DownloadStringAsync(new Uri("http://search.twitter.com/search.json?q=" + keywords + "&show-user=true", UriKind.Absolute));
                // wait 10 seconds beofre getting new twits
                System.Threading.Thread.Sleep(10000);
            }
        };
        worker.RunWorkerAsync();

，但它不工作。请帮助。