We need to look at the heat generated by your components, the speed of the fans you want to run, and the size of the radiator you want to run, and from that we can figure out some estimate of what the air/water delta temp will be.
= 230 watts (estimate from a PSU calc)
DDC Pump = 18 watts
GTX 480 SLI = 500 watts (based on TDP)
So we have 750 watts (ish) of heat to dissipate. Using skinnee's review:
We can get some idea of how this radiator performs:
At a fan speed of 1000 rpm, you'd be looking at an air/water delta of 22c. This is a very high delta.... and I am not sure that the noctuas are as good against a radiator as yate loons, so it might even be a little higher. This is not going to result in good temperatures at all, and, well, 1000 rpm isn't quiet either. Adding the NB into the loop will only make it worse.
It would probably work, and probably have better temps on the GPUs than air cooling, but your CPU temps will be high.
Next option: giant single loop. Radiators add very little restriction/pressure drop to a loop. Adding more isn't really a problem, but you are already talking about a low flow loop with so much stuff in it. The advantage you have here however, is only one pump, and a pump is the noisiest part of a loop usually (esp a MCP355). The extra 2 radiators will help reduce temps quite a bit.
Last option: This is the best option from a performance point of view. Shove all your hot stuff into the GPU loop (and let them run a little hotter), and have a short, clean CPU loop. The major downside here is the noise from an extra pump.
Personally, I'd try the first option and see if it was acceptable to you. You can always add more stuff later as funds are available. I believe the first option will work, but don't expect great temps at all, and it may possibly limit your OC (depending on your chip of course).
Hope this helps.