title: Notify the UI Thread from Background Thread
body: <p>I am trying to download some pages in the background, whose contents will be inserted into a database.</p>
  
  <p>I need to do this on a background thread of some kind (either BackgroundWorker or ThreadPool, which is preferred due to the way I can queue things up), but I also need to update the UI when the jobs are done.</p>
  
  <p>How can I notify the UI thread that the jobs are finished on Windows Phone?</p>
  
  <p>I've seen someone use Dispatcher.beginInvoke, but it wasn't clear what he was using (either Worker or Pool)-- is this the correct way of doing this?</p>