Thanks for the replies and suggestions. First, I will try to answer your questions.
This graph was measured with the meter on its 80dBSPL scale and with the correct calibration file I downloaded from here. I am using cables like you mention and I think the problem may have been not getting a good contact initially. My cables are just barely long enough so there is a slight amount of tension when everything is hooked up. You guys are both correct; I did this measurement with the mains on - but you already knew that from looking at the graph didn't you?
I am at work now so I will need to wait until I get off work to play with it some more but I will do another series of tests with the mains off. I will also try moving them around, stacking, etc. and see what I get.
I am also seriously considering the purchase of a Behringer Feedback Destroyer but I'm not sure which to get. The DSP1124P seems like it will fit the bill and is less expensive but I'm not terribly exited at the prospect of needing to get the firmware fix. I don't mind the actual task of replacing the EPROM, I just don't like the idea of waiting for the unit and then waiting for the replacement EPROM.
I have also be considering adding bass traps in one of the rear corners like I have in the two front corners. I can't do both back corners because I have a door in the way on the left rear wall. I do plan to cover the whole front wall with the same acoustic panels I already have on a portion of it to combat some reflections from the surrounds when playing at high levels. I will probably add another row (above and below) to sides walls and extend them to the front wall while I am at it. I guess waiting for the DSP firmware fix isn't that big of a deal since I will need to measure everything again after the additional wall treatment anyway.
Another thing worth mentioning: I have ordered a new sub and will be getting rid of the two PW-2100's when it comes (probably by the end of the month). The replacement sub is an Elemental Designs A5 - 350. I have read some pretty good reports on this sub so I'm hoping it will be an improvement over my current setup. If not, I will sell it and keep what I currently have (or if they all sound really good together - keep them all, Bwaaaaaa ha ha haaaaa).
I do have a question for you guys. I have two ButtKickers mounted to the floor joists of this room that are running off of a ButtKicker power amp. I didn't have it on during my measurements. What is the best way to take tune for them? Should I do an initial measurement, and appropriate corrections, and then bring them online after the "real" subs are corrected and fine tune from there or do one measurement/correction with everything on.
I'll upload a new graph, or graphs, with my findings from the activities tonight.
Thanks again.