if u want real good speeds dont use the actiontec wireless... either try to get an alu modem from telus when they install it and use a router with 802.11n perferably with the 5ghz channels or hang another 802.11n router off of the actiontec and disable the routing features on the new router and use it as an access point... either way u should get your own router with the 5ghz channels to use for wireless. also make sure u upgrade the cards on the computers to 802.11n with 5ghz support
First understand that optimizing Wifi and optimizing your DSL connection are mutually exclusive things. Sounds more like you want to squeeze the most out of your Wifi to bring it inline with your connection speed.
While her wireless reports 35-55mbp/s download speeds, you won't be getting those speeds. The reported speed vs real world is usually a wide delta. Real world, with security enabled, I doubt you are pulling down more the 10-20Mbps.
I have a 802.11n wireless AP in the same room as my laptop, and have it reporting 130Mbps when connected. I get closer to speeds you'd call 50Mbps when transferring off my network. This speed falls off quickly as the laptop moves away from the AP. This also fluctuates due to the amount of wireless networks in my building. 140 unit apartment complexes have this kind of problem.
Want guaranteed speeds? Use a guaranteed system (wired). Wireless will fluctuate, and I had to do a decent amount of finagling to coax that speed out of my 802.11n connection.