Not all components will go in the base unit. The biggest heat generating one, the power amp, will be in the basement roughly below the left wall you see in the image. That's where my equipment rack is which also contains the computer and NAS that serve and record my media/TV. The computer/server is the next biggest heat generator as well as noise maker, so it's been in the basement all along.

The base unit will only contain a pre-amp in the left cupboard and in the right cupboard the IR distribution block, the SageTV HD Theater (extender), a Wii and probably a DVDO Edge video scaler. I've got vents cut into the bottom and back of the base unit as well - the doors on the front will also sit about 1/8" from the front of the unit. Not a ton of ventilation, but it should be OK for the components that will be housed in there. The unit is 15" tall and 20" deep with each compartment being 24" wide. Lots of room. The side with the pre-amp has only a half back and the wall behind it will actually be recessed an additional few inches to make extra room for the XLR connectors that go down to the basement through the wall.

There are still a few specifics to work out in the design, but I'm getting there.