I use the Logitech 5.1 too. I think it is very crisp sounding, and the woofer is pretty nice for only being a 10". I'm pretty sure it's the Z-5500. But I have had all good experiences with these speakers, easy to set up, never had any technical problems from them. I got them for about $230 but this was about a year ago. I'm not to sure about the hooking up part either, but on mine I hook all my speakers (Left's, Right's, and Center) to an amp which is in the subwoofer box, then I run a wire from the subwoofer to the "receiver" and that is where I hook up 3 wires (Front's, Rear's, and Center & Sub)from that to my computer.
I may have not wrote that right or something so here is a link to the manual for hooking it up.
I just know I only have to hook 3 wires to the computer, and I can also hook my consoles or dvd player to the "receiver" too, to get surround sound.
I don't know but I think your system would be a "6.1" because 5.1 systems have 2 rears, 2 fronts, 1 center , and 1 subwoofer, and then 7.1 systems have 3 rears, 3 fronts, 1 center, and 1 subwoofer, then from what I read your system will have 2 rears, 2 fronts, 2 centers, and 1 subwoofer? I don't know I think I might be confusing myself. I wonder how your system would sound though, would like to hear your feedback if you get it hooked up, but I understand where your coming from by wanting to customize your system. One of my friend's has 3 subwoofers, and about 9 speakers hooked up to a recevier that is hooked up to his computer, it bangs, but I can tell you it doesn't sound as clean as mine. He just hooks one wire up from his receiver to the computer though, so I think that may have something to do with it too. But if you do get your system working JL please post your results.