Moving into house w/ pre-built media room- question about speakers

Hi all, in around 20 days we'll be moving into a house w/ a glorious media room. The sellers are leaving an epson 7500ub projector and 110" screen- score! Also, there are 6 surround speakers built into the wall w/ mesh covers (so I haven't been able to see what the model is yet). I have had a surround setup in my existing house for years, the traditional 5.1 variety. What I'm trying to understand is- are the 6 surround speakers in my new media room part of an incomplete 7.1 setup where I'll need to provide my own center channel and sub, or are the two front l/r supposed to account for a center channel as well? I would guess that may depend on the speaker type. I'm just throwing this out there for thoughts and suggestions so I have a better idea when I move in. I will happily plug in my own polk center channel and sub if need be, but if there's something I don't know about modern home theater design and implementation I'm happy and eager to learn from the pros here. Thanks!

Thanks for the replies. There are two l/r speakers on the front wall where the screen is. Then two more about centered in the room, and two in the back.. I think they just have all the speaker wires poking through under the screen which will be hidden by a media cabinet. I don't remember seeing a connector plate. Sounds like hooking up my own center and sub is prob the way to go.. Unfortunately I'll have to skip the mids for now and do 5.1.. I have an older denon that doesn't do 7.1 ;(

Very interesting.. I'll have to do my homework on this as I've never done speakers in a series..Assuming that this can be done with the exposed wires under the screen and I won't have to manipulate anything behind on the wall? Also, do you know how this would affect audyssey setup if at all?. I suppose it would just play the test blips in both side/rear and adjust accordingly and not thoroughly confuse it hopefully.

So my assumption about not having to do anything behind the wall was wrong I suppose. Hmm- we'll have to see- if it takes a lot of work I'll prob just run 5.1 for now. On the actual wiring you described- are all wires still the same to the avr except there is an extra wire for the red to black series? In other words- do those two terminals end up having two speaker wires? Or, is there only one speaker wire home run to the avr from those 2?

Forgive my ignorance on the series wiring, I've just never done it before.. So I'll twist the plus / minus wires together, cover with a wire connector and plug the remaining ones into the receiver? Also, you mentioned the left, I'm assuming I'd need to do the same on the right?

Thanks- that seems to back up what I was thinking a couple of posts ago. I was just thrown by the "What you merely do is find the two sets of wires for the speakers on the left side" comment. This will need to be done on the right as well yes? Thanks for helping out fellas.

Cool, thanks for the confirmation.. I made a post over on the thread for my denon to see peoples' experience with audyssey config and series wiring.. Anxious to see what they have to say.. Also, current house appraisal got done yesterday- last step our buyers have to approve before closing time on the houses.. Wish me luck!