You can definitely cut the cable dependence. We already had a PS3, so we do Netflix streaming via the device, plus its a blu ray player as well, so we watch Netflix DVDs on it as well. We have Time Warner Cable at $60/month for their fastest internet.
We bought a $15 antenna from Target and it works great receiving HD channels.
For sports, you can get some stuff on ESPN3.com which they offer to residential customers using certain high speed internet providers. I also hear you get some sports shows via Veetle.com, its hit or miss whether you can get the event you want.
Finally, we picked up a $45 DVI to HDMI converter to stream anything on the Mac to the TV. This also works great for any shows available online.
Its been about 6 months since we cut cable and rarely miss it
