a couple i have seen (and might be guilty of thinking myself):

1. temps in the loop change from component to component (20C drop after rad, 20C increase after CPU, etc) <---- EPIC FAIL loop maintains constant temp within .5C throughout loop

2. **all** prefab WC units/kits suck <---- no so much: some do, but others are actually pretty decent performance per dollar (especially the kits that come with double/triple rad)....and once the prefab units start coming with at least a double radiator they might be pretty good as well!!

3. i've heard the one about the bigger res makes better temps, but it's an older myth <---- FAIL it might take a little longer to max out water temps, but they will still reach the same temp as with a smaller loop - this is only true if you don't let the loop reach max temps (take reading too early)