Your internet speeds won't effect anything to do with gameplay or anything local on your machine apart from how fast your machine downloads updates/downloads games/sync's game data. Your downstream is adequate for that.
But when it comes to streaming - it is heavily dependent on your internet upstream which is incredibly low for today's needs. It would be worth speaking to Telstra to ask if you can upgrade to a package that can offer a considerably higher upstream like 5 or 10mbps. I have a 50mb down, 20mb up connection in the UK.