I would be looking at a Denon, Marantz, or Yamaha Reciever. AVR at that price range will have plenty of clean power for a two-channel system. Listening to movies and TV is just fine in 2.1. A good two-channel setup will sound much better than a middling surround sound system, so I wouldn't worry about going surround sound. Everything will still sound great.
A center channel is good if you want the sound anchored to the center of the system, for example when someone is talking in the movie, and you want the voice to appear to come from that location. In a two-channel system, if you are not listening at the 'sweet spot,' a point equidistant from both speakers, then the soundstage will be weighted heavily toward the speaker that you are close to. So if someone is talking is a move, and you are not right between the speakers, the dialogue will sound like it's coming from the speaker closest to you.