Good luck with the cool quest. You might consider setting up a refuge room, with its own air conditioner, for situations like this.
If it happens to be someone's bedroom, they will be most appreciative -- until everyone else crowds in!
We had a window unit in one room in OK, but haven't needed to here. We're talking about putting in a dual-zone system next year, if it looks like we'll be staying long enough to appreciate it. Our history suggests we'll be moving (somewhere ...) around February 2007, because we always move when the second baby is about a year old!