One HD is a free to air digital sports channel that shows on average 4-5 NFL games a week. All live from 4.30am through to lunchtime. They will often replay them later at night. Each week you will also get 1-2 MLB games, also live, as well as at least 4-5 NBA games (although due to contracts their play off coverage is poor). You don't get much of a say in what is shown but considering it as available on regular free to air tv, it is often better than what you could access in the states.
If you decide to get pay tv/cable it will cost about $70=100/month and you will get pretty much anything you want on 5-6 sports channels, including espn. Foxsports has 3 channels and will show most NFL, NBA and MLB games live during the day as local sports for obvious reasons aren't on then. If it is a weekday, and there isn't a local event on, most pubs are more than happy to tune the television to what ever you want. I particularly enjoy Mondays at the pub, steak and beer with lunch and 2-3 NFL games while I sit in the beer garden, soaking up the summer sun (that's right mother fuckers, summer football).
Australia is a sporting country. They don't just have a single football in winter, there are 4 major codes that a lot of people will follow. It is nothing for me to spend a a weekend watching NBA Friday lunchtime, Rugby union, rugby league and Aussie rules, with some English premier league or Italian Serie A thrown in, pretty much non stop through to Sunday afternoon. You can't really compare America's insular sporting habits to the rest of the world. If you can bet on it, it will be shown live, with plenty of people far more knowledgeable than your average water cooler jockey back home in the States.