However quiet or cool you want to make it...
Pumps can be perfectly quiet. D5 running at a low speed should be near silent.
Then it's just the fans that make the noise. Up to you whether you want to go for low rad area, high fan speeds, or high rad area, low fan speeds. Or a mix of the two.
Tbh - looking at your rig, I'm not sure why you'd build a new one.
It's still completely up to date. only change would be for 2011, which I wouldn't really bother doing at this stage, and more / different GPU. Not too sure why you'd need to rebuild the entire system for either of those tbh.