ASP .NET 3.5 now allows ATOM and RSS Feeds to be read without using any external libraries. This is achieved via the SyndicationFeed class. For example, to read from a URL

XmlReader reader = XmlReader.Create(feedUrl);
SyndicationFeed feed = SyndicationFeed.Load(reader);

This is not limited to URLs. XmlReader.Create() will take a String, Stream, TextReader, and XmlReader.