What setup do I need?

Have a room that's 20x14', with a 55" TV at one of the narrow ends. The ceilings are vaulted, maybe 13 feet.

Would use mostly for music and TV, movies, sports et cetera. I have an HD box from Cox Cable and a PS3.

I do NOT currently have any form of internet in the home. I currently use my cell phone to wirelessly tether.

Curious if I need a router/internet to make sonos work and which models would be recommended.