Based in large part on the reviews of Puget's Serenity on SPCR, I went ahead and ordered one for myself with a few changes, most notably the GTX 460 video card as I intend to use the system for mostly gaming and some work:
Asus P7P55D-E Pro
Intel Core i5 QUAD CORE 760 (Lynnfield) 2.8GHz 8MB 95W (Socket 1156 45nm)
2 x Kingston DDR3-1333 2048MB
EVGA GeForce GTX 460 1GB
Western Digital Caviar Blue 500GB
Lite-On 18x DVD-ROM SATA (black)
Antec P183 (Gunmetal Finish)
Antec CP-850 850W Power Supply
CAcoustiPack Acoustic Composite Sheet Package
Antec P183 General Quiet Modification Package
Windows 7 Home Premium 64-bit OEM
According to Puget's build system, my configuration matched their certified Puget Serenity Home. (not the SPCR edition)
Here is a picture of the internals of my system provided by Puget:http://www.pugetsystems.com/pic_disp.php?bid=52315
The ordering process went smoothly and it took them 5 business days from the time I placed my order to ship out my system. When the package finally arrived, I eagerly unpacked it as I was excited to "hear" just how quiet the Serenity would be. I had very high expectations based on the reviews on SPCR as well as Puget's own measurements (20dBA for the Serenity Home).
The system was packed very well and it took me almost 10 minutes to pull out of the double-box packaging and remove the foam placed inside the computer to keep components from being dislodged while in transit. Finally, I hooked everything together and turned it on.
Unfortunately, I was surprised to hear a very audible rush of air that sounded a lot louder than 20dBA. To be fair I don't actually know what 20dBA sounds like but assuming the ambient noise in my room is at 45dbA, I was surprised that the Serenity was noticeably audible. I expected not to be able to hear it from my sitting position, but it's audible from 8 feet away. I intended to use this computer during the day for work and gaming at night, but at the moment it's too loud to work with during the day.
I currently use a 2010 Macbook Pro for work and the only noise I hear from it under light use is the occasional hard drive seek noise. Were my expectations too high to expect at least the same from the Serenity? The Serenity is about two feet away underneath my desk.
It's not all bad news. When I tried to play Starcraft 2 on the Serenity, it did not get any louder even at the highest settings and 1920x1200 resolution. At least in this regard, it is significantly better than the Macbook Pro which sounds like a turbine engine under load.
I'm still working with Puget to resolve the noise issue and will update this thread as necessary.