Although not comprehensive, there is a nice RSS reader integrated in Outlook 2007, and you can enable your users to add feeds to it by simply publishing the link to your rss feed as a link with 'outlookfeed' instead of 'http' like this:
outlookfeed://dotnetjunkies.com/WebLog/andrewwhitten/rss.aspx
It doesn't support many of the tags, but here are the basics:
- <Title> - Name of the post
- <Description> - The main body of the post, can be HTML
- <Author> - Who wrote this
- <PubDate> - When post was published