And the point I am making is that, no matter how you transport that heat through the case, the volumetric air flow to *remove* it from the case has to be the same no matter what.
Liquid cooling allows you flexibility in design, and the ability to avoid having multiple huge heat sinks. You only need to have *one* huge "heat sink"/radiator (whichever terminology you prefer; they perform identical functions in a near-identical manner). However, if you need 14 CFM blowing through your laptop to cool off your two 3GHz processors, moving that heat to a central location and blowing air across one heat sink doesn't change that fact: you still need 14 CFM of air blowing in!
That having been said, yes, air blowing across one properly-designed heat sink will emit a bit less noise than having the same amount of air blowing across the rather jagged and obstructed surface of a motherboard, heat sink, hard drive, etc space. I don't think most of the noise comes from this source, however; I believe (perhaps unjustifiably) that most of the noise is just from the fan operation itself. I base this solely on the experience of hearing an empty case's fans start up, which was fully as loud (perhaps even moreso) as a loaded case with its fans on.
Also, remember that your liquid cooling mechanism will generally have a pump instead of relying on convective flow (especially in a might-be-running-upside-down laptop environment). Such pumps tend to add more noise again. And they add a small amount more heat to be removed, for whatever that's worth.
What liquid-cooling buys is flexibility, not less heat generation, not magical transport of heat away from the case without moving air, etc.
