Mr D: some months ago I accidently bought a "build your own PC" magazine intended for gamers. Inside was a mega test on CPU coolers. Surprisingly the water coolers didn't come out best. Considered pricey, cumbersome and not offering that much of an advantage if any over pure air coolers.
If I may beg indulgence from the Mods, the recommended best buys were as follows:
For the AMD and the Intel CPU, the Thermaltake Frio
For the Intel CPU and you want quietness, the Cogage Arrow
OFSO