and near future - 360 rad
with an 1800, i think you can cool something like 40 CPUs!!! i'm sure you won't need an extra rad! if you're getting high temps anywhere, there's obviously something else wrong.
not sure you should be judging your flow rate with one of those visual flow wheels, you're better off getting a flow sensor from AC, that way you can make an accurate judgement as to whether or not you need an extra pump!