I've watercooled various systems over the years, using kits ranging from numbingly difficult to install, to the more recent consumer-level ones by Corsair. My overall view is, it's fun to do but there's no real advantage for the average PC. But since it's fun as said, I still do it :-)
Since you're concerned about fan noise, perhaps you should work out exactly which fans are noisy, and then see if they would be replaced if you were to install a water cooling kit. If the noise is from the case fans, you might simply consider better-designed and larger fans, if they'll fit. Stock fans can be very low quality indeed.
I built a near-silent PC for a client, using a triple-skinned Antec case designed for noise reduction, a PSU with an oversize fan, and 4 slow-running 12 cm fans rather than the stock 8 cm unit. I considered a fanless PSU but couldn't find an 850-watt unit.
There's a lot of information out there on completely fanless systems, too.