I just added up what you listed and came up with a liberal estimate of 333 watts for everything in your system, and that is when everything is running simultaneously.
That's about what I suspected. Even with watercooling, its tough to pull 400 watts on a desktop system. Servers and SMP boxes with large numbers of hard drives are another matter. But for a single proc desktop system, you have to cram a lot of gear inside to make a good 400W PSU sweat.
Notice the word good. A lot of PSU makers hype peak power levels but don't deliver. A good PSU will actually be able to deliver the advertised power at the peak of the listed operating conditions. My PC Power and Cooling Turbo Cool 450 is guaranteed to deliver 450W at close to 120 degrees farenheit. At room temperatures its actually good for close to 530W.
A cheap PSU will hit its advertised output once in the lab. It's easy to buy a "400W" PSU that can't make over 250W at gunpoint. The key is picking a brand with a good reputation for quality. Sparkle/FSP is my pick for a PSU under $100, and PC Power and Cooling if your budget is over a c-note. I guarantee a Sparkle/FSP or PCP&C 400W PSU will do the job for what you are putting in your system and have power to spare. Antec? Some people around here love them but the defect rate is too high for me to endorse them. You do not need a 500W PSU-period.
One last note about your fans: There is a point in every air cooled setup where adding more fans or volume only increases the noise. I don't know what kind of case you're going to use, but I strongly suggest what you have listed is way beyond that point of diminishing returns. You might want to think about starting with fewer fans and adding them until you find the best balance between noise and performance.
BHD