I would start with a 2.1 system for now, and later on add a center and surrounds.
You are spending way too much on a receiver, it should be about 20-30% of your budget in this scenario. I would recommend a manufacturer refurbished unit from www.accessories4less.com
, it will come with a warranty and is a good way to save some money. This Denon would be my choice: http://www.accessories4less.com/make...uetooth/1.html
Now you need a sub, Polk is not known for it's subs, and I would avoid that one in favor of something better. Take a look at the SVS PB-1000, probably the best movie sub at it's price, and this is the point where you start getting good bass. It will dig much deeper than that Polk, sound better, and have better output down low where it matters.
With $300 left, pick up a pair of bookshelves, there are a lot of good options here:
HTD Level Three
HSU HB-1 MK2
Boston Acoustics RS-260 (A4L)
I consider all of these in a tier above the Pioneers, and that SVS sub will stomp all over the Polk. This will give you a good start, and later you can expand to 5.1.