Ehh, not yet. The all-in-one type setups like this are getting very close to being competitive with high end air setups as far as actual $/cooling goes. The main advantage of these things is less clutter in your case, which can help make airflow better, but is mostly just for looking all riced out through the side window.
-1 star for completely skipping the hardest and most time consuming part of building a computer.
I've got a K�hler H2O 620 that looks like the one here, it is quieter and keeps things less than 30F above room temperature, good for overclocking, but you need a case designed for it. The big radiator acts like a reservoir and should have both a push and pull fan on it, connected to the CPU fan header, so they can run slower.