I changed from a cheap case with 5 80mm fans to a P180 last week.
Definately quieter but took a lot of effort to build and mu 12v ATX cable only just reached by passing accross the back of the heatsink.
I also installed a thermal take big typhoon which is a tight fit as it's huge.
I moved the fans, my psu has 2 fans, 1 80mm with speed adjustment and 1 92mm auto speed adjustement so I took the lower section fan and fitted that to the rear exhaust then used the rear exhaust fan as the infeed at the upper 120mm mount.
With all fans set to low there is a quiet rumble, this is noticable louder switching to the medium setting. moving to medium only shaves 1deg C off the CPU load temp so I prefer quiet.
With the old case I could hear the fans from the next room, with this one I can't from more than about 5 feet.
I've also notice that the DVD has suddenly become very loud when it spins up, proberbly as the case is quiet.
It's far from silient but it's about as quiet as can reasonably be.
Disk drive is barely noticable , and I can now hear the whine of my GTX
AD