The Big key factor is speaker sensitivity ratings. Klipsch and Paradigm are probably your best bets as those two brands seem to offer the most efficient line of speakers around. Both are excellent brands but I find in my opinion the Paradigms more musical sounding with a more expansive sound stage so I am little more partial to them. When it comes to movies, the Klipsch seem to take the cake. Remember, for every 3db less the speaker is rated, it takes double the wattage for it to play at a given volume level. Ultimately, try to acquire speakers with sensitivity ratings at or above 90db. I know some people may like Sony receivers, but I personally would recommend if you can, is to return it and get something better like an Onkyo, Yamaha or another Denon. They have models that run at a similar price point and their power ratings are usually based on a full 20~20khz scale unlike Sony's that love to boast their so called big rating on a narrow 1KHZ input. Again, in my opinion, Sony receivers have a cold sound quality to me that seems harsh.