We have decided to get whole house A/C and since we don't have cold air returns on the second floor I am wondering if it would be cool enough up there if we get conventional AC. The Mitsubishi system is too expensive and I don't like the idea of drilling holes in the brick and having pipes running on the outside of the house. So for those of you that have conventional AC, is there much of a difference in the cooling temp between the first and second floor? Do you need to supplement with window air conditioners? Thanks! Karen