How can I get started making a C# RSS Reader?
See
http://msdn.microsoft.com/en-us/library/bb943474.aspx
http://msdn.microsoft.com/en-us/library/system.servicemodel.syndication.syndicationfeed.aspx
http://msdn.microsoft.com/en-us/library/bb943480.aspx
Basically there is a lot of stuff in the .Net 3.5 framework that does the grunt-work of parsing and representing feeds; it's not hard to write a 30-line app that takes in a feed URL and downloads the feed and prints the title and author of all the items, for example. (Works for RSS 2.0 (not others!) or Atom.)
As another poster recommended, the SyndicationFeed class and Argotic are the best alternatives.
If performance is an issue, the SyndicationFeed class will be much better. I benchmarked it as being about 9 times faster than Argotic on my hardware.
The problem I've had with the SyndicationFeed class has been its ability to successfully parse any random feed from the 'net. It fails with an XmlException surprisingly often.
For my uses, I'm sticking with Argotic. After all, it is open source, so I can always make changes if I need to.