I've noticed that coolermaster has a new passive cooling solution for CPUs, which works with heat pipes. If the passive solution isn't good enough, one can always add a very slow-moving fan to the thing, to minimize noise.
As for VGA cards, Zalman has a passive thing for those too. I've seen one of their systems on a Radeon 9800 pro, so it's definately good enough.
In other words: look around, it's out there.
