Waste of time effort and money if you ask me.
Just cpu watercooling - especially a cheap kit will be rubbish, certainly hardly any cooler and no quieter than decent air.
A decent heatpipe cooler with a quiet 120mm fan will do the job just as well and save you dosh.
The water cooling will use a fan of similar size and noise and have the pump noise/vibration too.
Only benefit I can see is " ooo look at me, I've got watercooling"
Do it right or not at all.
- I am assuming that you are a typical OCUK user and have a relatively cool running A64.