while im still getting my feet wet in the high end computer field, i'm a mechanical engineer and specialize in heat transfer. i was impressed by the symphony by thermaltake. it's one of the few liquid cooling systems on the market with dual pumps. (the last thing you want is a pump to fail when you only have one!)
i really dont understand why someone would build a liquid cooling system with a fan inside of your case, one reason for liquid cooling (besides way better heat transfer) is to reduce noise levels.
I symphony relies on natural convection on the non-liquid side of their external heat exchanger (no fans) so the only noise it makes is the pump vibrations, which is minimal. Its going to cost you between 200 and 300, but it will be worth it for silent super cooling! go to www.thermaltake.com
for some really cool liquid cooling solutions.
For the product you are looking at, the exaust is simply the outlet from the heat sink. it is a closed loop, so the water wont be going anywhere except thru the fan area and back across the heatsink. this type of water cooling does not cause the water to evaporate at all, it will stay in the liquid form. evaporative liquid cooling is conducted at low pressures. liquids evaporate at lower temperatures at low pressure, but the latent energy of vaporation is higher (in laymens terms, it will evaporate at low temps, but suck more heat from the chip in the process). the vapor then moves (using natural boyancy, i.e. hot air rises) to a cooler part of the computer where the heat is dissapated and the vapor becomes a liquid again and is reused. i've seen this type of liquid cooling used on 3d accelorators, but are expensive as a ton of R&D goes into every design. (i think their called heat tubes or something) i got this info from Heat Transfer II class... sorry if some of the terms dont make sense, u'll just have to trust the engineer .