I used to connect my laptop to my TV, but didn't have enough inputs, so it was a pain in the butt. I had to switch out something else. On top of that, my laptop wasn't dedicated to TV watching, so I had to power it up each time to, say, watch Hulu. That and I didn't have a wireless keyboard or mouse, so I had to get up anytime I wanted to pause, etc.
Now, if you had a dedicated pc (eg HTPC) and were using Windows Media Center, Boxee, or Playon and had a remote, it would probably be quite useable, but unless you have an extra box lying around, it would probably cost a 2-3 hundred to build a decent one.