I'm actually using a System 3 Gitzo, so not quite as beefy as Hal's.
In practice, I actually wind up taking the camera off the tripod and shooting handheld, and just using the tripod for the laptop the vast majority of the time. This is primarily a setup for when I am on location. When shooting tethered at home on a tripod, say for product shoots, I usually put the laptop on a separate table.
I heard your concerns re vibration, etc. The fans will be an issue. Hard drive is not, as I now have a MacBookPro Retina, so with the exception of fans, no moving parts!
Do you have any thoughts re Gitzo, Manfrotto, or TetherTools (or other) laptop platforms?