I've been looking around for ways to watch TV on a computer for free. It's much easier for me to work a computer than a TV. The other day I found Hulu, a beta site that is issuing invitations for people (U.S. only) to watch full length TV programs. There are limited commercial interruptions during the shows.
Here's how it works: you email them to be put on a list to get an invitation. The wait seems to vary. Right now I don't have much time to watch anyhow, but will let you know how long it takes for me to get an invite.