Yes you can have a 7.0 system that rocks on movies, and music especially if you own Hybrid type or completely active speakers. All Passive guys will need some serious power to overcome the disadvantages of a passive design, no matter who makes the speakers.
A subwoofer would be an improvement to nearly anyone's system though, mainly due to the fact that where a speaker sounds good for midrange performance is most likely not the same spot for the best bass, even with five to seven bass sources. And the obvious, .1 is a subwoofer channel designed to run to a sub with its own volume controls etc.. so distributing the .1 channel does cut down on some flexibility in setup.
Perfect-Ideal-competent-adequate-good enough all subjective terms, subwoofers in a properly designed system dissappear and become one with the Satellite speakers, especially in surround systems. Even if the Satellites are capable of incredible bass output, a Sub can help merely by increasing dynamic range and better room response/ integration. BUT! your system can still kick butt without a sub.
Reality Check------
This thread is a clear example of how misunderstood multichannel sound is to the average home user, and the dealers who try to put together the systems for them.
Walnder and Aroc with just crazy presumptions about movie sound and center channels and subwoofer quality. Most of my "theaters" sound better (playing music from CD in PLII) than the pathetic I mean carefully crafted "audiophile" systems I hear in people's homes. Multi-channel is something you can't slap together like a 2 channel system and call it art like we seem to do here on audiogon. It requires and understanding of how the components work, and interact and this cannot be done by "feel". Either you know it or you don't. Clearly by your "opinions" and funny statements you have not take the time to get aquainted with these design parameters. Thus you're trapped with what you know. And unwittingly have joined the "Chadnliz Theater Philosophy Club" the motto, "Loud, Proud and Wrong"
Sorry for you both, I am