I use a MythTV box, no cable subscription, but netflix and hulu. But since Netflix streaming uses Silverlight and isn't supported on Linux, I get snail-mail DVDs from netflix, which I don't mind so much.
IT's also a spiffy media server. My entire DVD and CD collection is burned to it and available for playback anywhere in the house.
So in spite of a few drawbacks, it isn't overall a bad solution.
Real programs don't eat cache.