If you're an HTPC user that wants to start viewing premium HD content on your PC, Media Center with CableCARD is the way to go. Allowing you to view not just your local HD broadcasts but premium channels such as HBO or Showtime, CableCARD is the best way to get this content into your ecosystem.
Other than the purchase of a CableCARD tuner, there's one other step you'll need to take in order to enjoy this content in Media Center: Passing Microsoft's Digital Cable Advisor Tool (DCA). The tool tests your PC to ensure that you meet certain standards that will provide the best experience possible when viewing or recording HD content. The steps for running the tool aren't difficult, but passing is required if you want to add CableCARD to your HTPC experience. Here we'll walk through installing and running the DCA on your PC.
The Digital Cable Advisor can be found in the Extras Gallery within Windows Media Center. Simply select the logo and hit OK on your remote and the test will begin. (The entire test can be completed with your remote so there's no need to grab a keyboard and mouse to run the DCA.)
If you're using a laptop, be sure you're not on battery power before beginning the test. As well, you shouldn't be running any other applications at the time as this will affect your results.