I think Telstra used Speed-xxxxx before they started using Thomson (perhaps they considered that an upgrade) :)
If you are using some form of ADSL I see no reason why you can't use one unit to provide modem and router functions. Of course, knowing the ins and outs of how to configure your modem/router make all the difference in these situations, so that you don't have to rely on the ISP to set it up (and charge you for it). They will say all sorts of lies to cover their backsides, or to make their jobs easier. Only if you've studied IT and Networking yourself can you discern what is and isn't possible.
Anyway, back on track. I used to be with iPrimus, then switched to Telstra earlier this year. I went from a Netcomm NB5 to the router they gave us. Multiplayer gaming was then pretty much impossible due to massively high pings over 800ms. After a month or two I bought the newer Netcomm NB6 which is officially supported by Telstra (http://www.netcomm.com.au/products/adsl-broadband - pick whicher NB6 has the extra features (i.e. WiFi, gigabit LAN, etc) for the specs). As soon as I switched, everything was fixed and much faster. It's my belief that the Telstra branded routers (A) allow easy setup for home users that are computer illiterate, and (B) allow Telstra backdoor access and provides a way to throttle traffic perhaps (could be wrong there).
Anyway, ummm, back on track (again).
As an intermediate possible fix, you can search the Speed-whatever website for new firmware for your modem and possibly also grab new firmware from the Netgear website for your router. Netgear is a good brand, but it's still better to use an all-in-one modem/router device so that security settings are already setup just right from the get-go. This helps prevent intrusions, and/or prevents connectivity issues on your network due to strict security settings.