I first built my Media PC with a single tuner even though I knew I probably would want to add more later. With my cable DVR I had grown accustomed to having two tuners, so it was hard going back to only one. Fortunately, with Windows Media Center, adding tuners is easy (and cheap).
Why two tuners? Even though I rarely record two programs at once, it is nice to know you can. Even more likely is that I'll want to watch a program while another is recording. Of course, you can also record two programs and watch any pre-recorded content you like (or any web-content for that matter). You can even go crazy and add up to 4 digital tuners (that should be enough for most people!).
So, what is the cheapest way to add more tuners? Turns out that a company called AverMedia makes a dual digital TV tuner for about $60! If this dual tuner won't work for you (see below), there are alternatives at about twice the price (still not bad).
So, go ahead and supersize your Media PC with multiple tuners! Here is how I did it.

