Basically, you'll need the whole bunch of equipment if your prebuilt cooling solution is not extensible. In other words: Pump, reservoir, radiator(s), tubes, coolers and fluid. Maybe some fan controller too, if you like the system to regulate temps (and thus fan speeds) automatically. Tube diameter and connectors depend on personal preferences, so you have to choose for yourself what you'd like to use.
The noise emission will depend on the size of the radiator. More cooling surface means less noise, because your fans can run at lower speeds (even if you have quite a bunch of them). Given the fact that you want to cool two 5870s, you'll need at least a 420/360 radiator to obtain decent noise (but I'd suggest an evo 1080 or aquaduct 720 for this purpose).