This has been mentioned lots of places already, but in case you missed it – ExtremeTech reviews six news aggregators, including NewsGator. A quote:

NewsGator provides an important convenience – operating inside outlook, it doesn’t require a separate application to view news feeds Since we use Outlook for email when using Windows, we found it super handy to have our news feeds embedded inside.. This is a unique feature to NewsGator, and if you use Outlook heavily, this product is for you.