Chris Lanier provides a tutorial on setting up the Media Center editions of Windows XP and Vista for automatic commercial skipping using DVRMSToolbox:
Everyone should know about DVRMSToolbox that lets you do just about anything with your Recorded TV files. However, the more time that goes by the more I see that people are not taking advantage of what DVRMSToolbox has to offer. Today I wanted to give everyone a basic introduction to one of the coolest features, automatic commercial skipping!
Get it while it lasts before the movie and TV studios find a way to rain on the parade.