The OP could look at
Playon, a media streamer that xbmc supports, and provides access to plenty of on-line content including Hulu, ABC, NBC, Fox, CBS, etc. There's an active plug in and script community that provides new content regularly.
It is a commercial solution, with an initial investment of something like $40 and recurring charges of $19 per year, but much cheaper than cable. You need something to serve Playon from (I'm using a WHS, but a laptop would work).
The problem with this type of solution is that it buries the content a couple of levels deeper. You would access it via the Video menu, then click on Playon, then navigate through their menu system. And as Poofy noted, the quality of on-line content from the networks and places like Hulu is considerably less than what you get from your HD channels on cable or satellite.