Take a look at NewsGator (http://www.newsgator.com/). It is a plugin for Outlook and works really great. You can download plugins for NewsGator to allow you to also post to your own blog from Outlook also (AFAIK there
is still no way to use NewsGator to comment on a blog post).
All in all, an awesome aggregator. I've been using it for a long time and love it. BTW, it also does NNTP news as well.