A few years ago, the girlfriend and I spent some time carefully building and configuring a MythTV box, which was fun. Then we proceeded to not actually watch any TV. 6 months later, when we realized we were only keeping the cable subscription so that our Myth project wasn't purposeless, we cancelled it.

We still watch a decent bit of downloaded TV content -- we'll sit down and watch entire seasons in a few evenings. We watch nothing in 'realtime' and we see zero commercials.

(I actually miss commercials and wish people wouldn't cut them out of what I download.)