I would suggest a quality 500W PSU for that system, if you're planning on say a more powerful CPU and GPU further down the line get a quality 650W PSU.
Calculators are a hit and miss but will give you a decent indicator.
As pointed out setting up the case with positive air pressure will minimize dust and go a long way so I would focus more on getting a case that's designed from scratch to be quiet.
I haven't looked at cases for some time and don't know if it's possible to get a quiet case that looks a bit more 'flashy' rather than looking like your everyday generic fridge or something.
I'm using Prime 95 (Version 26,6)
Newer versions of Prime makes the CPU run hotter, this version runs 10-13°C cooler.
Fuzzwinks pointed out a very nice feature with Intel Extreme Utility of being able to set it to run for a certain period of time. That's very convenient.
The aftermarket cooler was already in the system he was asking advice on. I did not add it as a recommendation therefore not adding to the cost of the build.That was the context of my quote that you "just" responded to.In any case, I'm sure that the OP has made up his mind by now.