Hey Charlu, those polk audio speakers will be great for a large room. That price you said you can get them for is a good deal. I'd get the Yamaha receiver between those two. It will be enough to power the speakers. You're going to need this type of audio cable to plug the speakers into the receiver: http://www.kongcable.com/terminated_speaker_cable_3102.html
one per speaker. you can buy a 50 foot spool of the wire really cheap from monoprice and the banana plugs seperately then strip the wire and attach the plugs yourself, but if you're just getting into home theatre, I'd just buy the cables pre-terminated from kongcable or a place like that. You may not want to get a subwoofer right away if you're getting large tower speakers, since they already have pretty good bass. You'd notice the subwoofer in movies during explosions but otherwise it's a pretty subtle enhancement if you already have big towers like those polk rti10.
Gear list: Main setup - Kef Q900, Svs sb12-nsd subwoofer, onkyo 609 receiver, epson 8350 projector, elitescreens sable 92" screen, mac mini htpc
bedroom setup: PSB Image B5, maverick tubemagic a1 amplifier, hifimediy sabre9023 dac, ZMF Fostex T50RP modded headphones
preordered gear: Light Harmonic Geek Pulse X dac and headphone amp