There you have it....you now have an excuse to buy the rest of your speakers prior to completion of the basement.
The only problem is that you have a chicken and egg scenario. Without drywall up, you can't really get a good sense of how your system is going to sound. However, if you wait until that point, you can't go back again and do your wiring. Hopefully, your room is 'standard' enough in shape that you won't have any weird reflection points, etc. In that case, you start getting into the area of accoustic panels and sound dampening....fun fun.
As far as theater construction advice, you might want to start trolling over at the
Home Theater Builder section at the
AVS Forums. There are a great bunch of people over there that can answer any question you can come up with. It's also a great place to view other people's theaters and pick up ideas. I have learned so much over at that forum about anything from projectors, HTPC, electrical work, construction, theater building...you name it.
