So many programs feature a list of possible extensions and protocols under the \"Default Programs\" control panel applet. \"Set Default PRograms\", more precisely. (Vista &a
Your'e going to do this as part of the installation process for your application. If you're using WIX, you can configure following the answer in this question:
If you do want to do this through code, check out the following article. It is written using VB.Net, but the code is rather simple and can be easily translated to C#.