civguy, all the suggestions already made are good, but if there's any truly complete and effective way to prevent rust, I haven't found it. My shop building is uninsulated metal skin, wood frame, concrete floor, but it has a ridge vent and the eaves are vented all the way around, so I have the same problem you have. If they get too rusty, I used the wire wheel on the bench grinder and/or the glass bead blaster cabinet to remove the rust. When I finish with a tool, I usually wipe it off with an oily rag (and if I don't use it again for awhile, then it's coated with dust instead of rust). Naturally, the problem is worse if the humidity is high. My brother, being a tool distributor, has a big truck with the back end insulated, air-conditioned, etc., but when he parks it at night in the winter, he leaves an electric heater going in the back because if he doesn't, all the tools back there get cold, then when he starts up in the morning, condensation will form on all that steel and iron.
Bird