Yeah the panaflo, but I just ordered 3 of the new Enermax manually adjustable variable speed 80mm fans.
First off, theyre blue with clear blades. (there's also a pinkish version)
Second, they have three speed settings --- in conjunction with motherboard montor you can find what works best for you.
At max setting, the rating is 40cfm and 33db.
At mid speed, 32cfm and 27db.
At low, 25cfm and 21db.
You also get a chrome grill and a 3 to 4 pin adaptor. With the panaflo you get bare wires.
I want a quiet PC, but the ability to ramp it up if needed is very nice. One of these is going on my heatsink. one as case exhaust and one as case intake.