I'll third looking at HSU for the sub. I have both STF-1 and STF-2 subs and they're excellent. SVS is excellent as well, but tends to cost a bit more. The x-sub is a good option as well, but it's backordered till next month. For speakers, Boston Acoustics at Onecall, av123 speakers, PSB at DMC electronics, Mordaunt-Short and KEF at AC4L, Mirage at Crutchfield, Missions at TSTO. That's just a few off the top of my head that have some good deals going.
The Yamaha 661 is a great receiver. So are the others mentioned. It comes down to price and features.