Once you've picked that heat up from the silicon, you must do something with it, or you're just going to be circulating hot water back to the silicon. There have been folks who've made do without a radiator at all, just a large enough reservoir of water. Often it'll be ice water. But in a continuous running system, you'll eventually heat the water to the point where it's not cooling the system anymore. Eventually you've got to get the heat back out of the water.
Most people extract the heat from the coolant with a radiator and a fan.
Between the waterblock and the radiator, of course, you've got tubing, you've got a pump, and you've got a reservoir. The most reliable pumps are magnetic impeller pumps. They've got no shaft seals to leak, and leakage is a watercooler's nemesis. Then of course, you've got tubing and all the required joints, each one a potential new leak. Currently, there isn't much available in the way of professional quality kits or any such thing available for enthusiasts.