refrigman1, Thanks for the reply. When we moved in, 3 of the bedrooms had window unit A/C's, 2 of them mounted in the wall. Why would you need window units with central air (?) - it didn't click at the time and I didn't think to ask. Maybe the system is undersized?

The guy who gave the estimate didn't do a load calc. He just based it on the square footage of the house. He also went up into the attic and looked at the insulation and ductwork. The ducts are rigid galvanized steel wrapped in insulation covered with a brown paper. Don't know what the correct term is for that stuff. Thanks.

johnnymac01