I'm considering dropping Comcast cable TV because they recently cut off clear-QAM service in my area. I use a Mac with TV tuner. I can still get local and broadcast channels but no more basic cable (Discovery, etc). Comcast doesn't have analog service anymore so it's no longer possible to watch cable channels without a cable box. CableCard doesn't seem to be an option on the Mac yet and the DRM worries me.
Since then I've been relying more on Netflix, Hulu, and torrents. My computer is a Mac Pro tower, The software I'm using is EyeTV, Plex, and Front Row. It's really a kick-ass setup. I have a HDHomerun tuner and I plan to hook it up to an antenna soon.
I still have a cable box for a TV in another room but I'm considering replacing that with a Mac Mini or Apple TV.