If you're really interested in rear towers, Poison, I've gotta know whether or not your $600 budget is set in stone (or whether putting more money into the audio side of your home theater setup in later months is something you're interested in/willing to do). Also relevant is the type of listening you plan to be doing now and down the road. TV / gaming / DVD movies / Blu-ray Disc movies / music / other?
You are right in thinking that piecing together a system slowly, gives you a better chance of completing a "great" system sometime down the road, especially as you sound like one of us -- a "regular joe" with a real world budget to work with.
If near $600 is how much you want to spend on the sound system altogether, I would still recommend the Z-5500. Though it is not audiophile friendly, it serves it's purpose real well, and I expect you'd be surprised by it's competency in a variety of audio formats.
__________________
|