Thanks, but I guess I asked the wrong question.
What I really wanted to know was how to figure out how to find someone to guide me through the process, someone who has more knowledge than a salesman for a local heating and air conditioner company. I've watched some friends trying to fix up a house like the one I mentioned (typically, a one-story bungalow with just a crawl space), and been less than impressed with the contractors that have tried to make bids. They don't mention insulation or window/door replacement, they just try to sell hardware, sheet metal and some cheap immigrant labor. How do I find someone with a broader knowledge and repertoire of solutions without breaking the bank?