I just bought a radiator. It has more or less the same size of the Big Momma, but it's all aluminium. I heard that aluminium dissipates better the heat.. It was very inexpensive, so, if I don't like it, I'll just buy another one.
I bought it to a guy who told me that (not sure if it's true) it would keep the water 2ºc above romm temperature when cooling his Duron 600 @ 1000Mhz...