In contrast to one or two reviewers, I found this a pretty simple install. My motherboard is a Gigabyte GA-770TA-UD3 with AM3 socket. The brackets fit well and with plenty of clearance. The pump itself is small so should not interfere with any other parts like RAM (clearance can be a problem with larger fan and air based coolers). From opening the PC case, the whole process of taking PCI and graphics cards out, motherboard out, bracket exchange, fan and radiator install and then CPU pad/pump install, replace cards, testing and then closing up the case took no more than 45 minutes - and I don't have a removable panel behind the CPU so the motherboard did have to come out.
Cooling is very effective, even with my AMD Phenom II X4 965 running flat out on all four cores. The supplied fan is pretty quiet too (but replaced after a few months with a Cooling 11 bladed job, even quieter)
It is important to point out (although it is in the instructions) the pump must connect to a non-controlled fan outlet so that it always runs at full speed (it is extremely quiet, just about silent) and the cooling fan that blows air through the radiator should be connected to the CPU fan connector on the motherboard. That way, the fluid is always circulated, and the cooling breeze is varied according to the needs of the processor.
What more can I say - it just works. Five stars.
UPDATE July 2011 (after 18 months) - still works just as well as when new. I have had to blow the dust out of the radiator, but that's to be expected. And I have changed the processor - now a Phenom II x6 1100T - it runs just as cool as before if not better.