I want to comment on the discussion of PSU airflow that happened several posts back. I personally own and use an Antec NeoHE 500W (the new NeoPower series power supplies are the same, just updated for higher efficiency), and find that its single 80mm fan is almost perfectly as good for near-silent operation as the 120mm fan in the Corsair VX450W PSU.
The main difference here is that a PSU with an 80mm fan doesn't account for as much of the PC's exhaust airflow, so it's not drawing a large amount of warm air from the CPU -- just enough airflow to cool itself. A PSU with a 120mm fan will pull more of the system's total airflow through itself, so if your system is generating tons of heat, that heat is going to have more of an effect on the PSU's fan controller, and the PSU fan will rise and fall with overall system temperature. (Let me add that this is especially true if the case's other exhaust fans, for some reason, could not possibly move enough air on their own to keep the PSU fan from needing to spin up and make up the extra airflow needed.)
In my main PC, which has been designed from the ground up with silence in mind, I focus on having a rear exhaust fan that's capable of moving enough air quietly enough that I don't need to rely on the PSU for a significant portion of the total airflow. Perhaps what's telling is that the loudest component in my system (while at idle) is the Seagate 7200.10 hard drive, followed by my HIS Radeon 3870 card (which is just a smidge more audible than I'd like at idle). The power supply would fit in at number three, simply because my rear case fan and CPU fan are both silent at the low end of their fan control curve, and are set up to run intermittently as needed. The 92mm front case fan in front of my Seagate 7200.10 has never run (that I've seen) except on the hottest summer days in my old dorm room.