I live in the US as well. As far as I know things like apple tv, roku, amazon streaming, netflix all offer a wide variety of tv shows and movies, however you will not be able to stream internet content through them. Many network programs that aren't regularly broadcast shows aren't available through any of these services, and streaming only gets you so far.
I stream movies and a few tv shows from places like amazon on demand, and the video quality is ok (about 720p), but as of now that's about all you're going to get from a streaming source. Sound is not so bad if you are streaming from a source like amazon or netflix, from my experience, when you have the tv running sound to a receiver and then to your speakers. You can always divert sound from the tv speakers to something else by means of an optical out, rca plugs, or what have you.
It really depends on what you watch, and what your needs are. I think you need to narrow down what you watch most often, if a streaming service can meet those needs (in terms of available programming), and if the price of whatever subscriptions this entails is less than just adding it to your existing Bell service.
In my own experience the more "stuff" you you and the wider your tastes in programming the less useful streaming is. This is starting to become less true, but there are still plenty of items that are not available for good quality streaming.
I'm sorry for the slightly rambling answer, but I'm a bit unsure what I'm answering just like you are a bit unsure what you're asking