I do. I saved ~$100/month by axing Comcast and downloading torrents of all my favorite shows.
I built an HTPC for ~$600. I use MediaPortal to do playback. The plugins for it do an amazing job of automatically associating files with episodes, downloading art, keeping track of which episodes you've watched, etc. Similar stuff for Movies too. Throw in a Harmony remote and it's even wife-friendly enough that I don't have to do anything. I highly recommend it.
It does? News to me. It's been 2 years since I tried xbmc, and when I last tried it, a fairly decent machine struggled with HD playback while Mediaportal (and MPC and others that used avivo and purevideo). I did a quick search before posting to make sure I wasn't mistaken and saw this:
> Note! Developers wanted! XBMC does not yet support any listed methods of hardware accelerated video decoding.
So I didn't do more digging...but that page hasn't been updated so 2009, so my bad.
I highly recommend MediaPortal http://www.team-mediaportal.com/
The setup is significant, but once you have it going, it's great. You can use hardware accelerated h264 decoding (whereas Boxee, XBMC and many others are software only). The plugins for it have great, poweful support for automatically matching Movies and TV shows based on regexps and online lookups of the filenames.
Some screenshots can be found: