CPX, I have a PAA3 and will try and get an approximate reading of some of the servers I have running at home (might take me a day or two based on my schedule). They aren't Sun servers (just older PC's) but that might give you an idea. I'd try and get readings from a customers data center, but they won't even let cell phones in, so doubt I could get my PAA3 past the man trap.

You HVAC installer should be able to get and install dampners under the HVAC unit. Basically rubber pads that sit between the unit and the floor. It is important that the bolts that attach the unit and duct work to the floor/walls/ceiling are isolated as well.

I think I have some info on sound absorption material used in live sound applications, but again it is at home so won't be able to get to it for a couple of days.