I really can't comment on the five main speajers but this I will say: While "general" speaker manufactures are great for their areas of expertese, look towards specialized subwoofer manufacturers for your best bang for the buck. Two main contenders currently would be Hsu and SVS. You might even consider two subs.
Also, Look to spend a large percentage on the sub since that visceral feeling you get when the walls rattle and t he pictures become lopsided iswhat makes you appreciate your HTsystem.