Some good suggestions in this Ask MeFi.
We have a very similar problem – an office upstairs with two computers and two large people. Our solution is mainly based on a series of fans pushing air around the house, taped or tied in place to keep them safe from catattack.
We’ve been meaning to do a post all about it, so I’ll probably end up writing it and posting it just as the heatwave ends.
Oh, yeah, I found it through Lifehacker, obviously.