Ok, here are 2 builds one is the minimum I would recommend, the other is a more of a power build.
sources for prices are:
http://www.quietpc.com
http://www.newegg.com
I didn't shop around... that's your job
I just found good quality silent parts that fit together.
I didn't use any after market VGA coolers because this voids the warranty of the GPU. There are several cards that have after market style coolers on them that are very silent (under 35Db at full load) which are priced 'well' and you don't have to perform open heart surgery on the GPU to install the cooler.
The case I selected is the little cousin to the one I'm going to use in a build for my son. It is due in stores in Mid April, so I hope you can wait that long, if not I will recommend another case. Check the case out here:
http://www.fractal-design.com/?view=product&category=2&prod=58
its worth the wait.
Core i5 Sandy Bridge Budget silent PC
Case:
Fractal Design Define Mini Computer Case $120.00
Additional Fans:
Fractal Design 140mm Silent Series Fan x2 $38.00
MB:
ASUS P8P67-M PRO (REV 3.0) LGA 1155 $150.00
CPU:
Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) LGA 1155 $225.00
CPU Cooler:
Scythe Samurai ZZ Quiet Top-down CPU Cooler $35.00
RAM:
G.SKILL Ripjaws X 4GB (2 x 2GB) DDR3 1600 F3-12800CL8D-4GBXM $55.00
PSU
RX-6300 630W 15.5dB(A) Ultra-Quiet Modular PSU $130.00
GPU
MSI R6950 Twin Frozr II OC Radeon HD 6950 2GB (has a stock silent cooler installed) $310.00
SSD/HD:
OCZ Vertex 2 OCZSSD2-2VTXE120G 2.5" 120GB $215.00 (you won't be happy with only 60GB, trust me)
DVD/CD:
ASUS DRW-24B1ST/BLK/B/AS Black SATA 24X DVD Burner $18.00
OS:
Windows 7 Home Premium 64-bit OEM $100.00
----------------------
Total $1,396.00
Core i7 Sandy Bridge Power Build Silent PC
Case:
Fractal Design Define Mini Computer Case $120.00
Additional Fans:
Fractal Design 140mm Silent Series Fan x2 (top exhaust, side intake) $38.00
MB:
ASUS P8P67-M PRO (REV 3.0) LGA 1155 $150.00
CPU:
Intel Core i7-2600K Sandy Bridge 3.4GHz $329.00
CPU Cooler:
Noctua NH-C12P SE14 Top-Down CPU Heatpipe Heatsink with NF-P14 Fan $87.00
RAM:
G.SKILL Ripjaws X 8GB (2 x 4GB)DDR3 1600 F3-12800CL8D-8GBXM $130.00
PSU:
RX-7000 700W 15.5dB(A) Ultra-Quiet Modular PSU $142.00
GPU:
PowerColor PCS+ AX6970 2GBD5-PP2DHG Radeon HD 6970 (has a stock silent cooler installed) $375.00
SSD/HD:
Crucial RealSSD C300 128GB CTFDDAC128MAG-1G1 $265.00
DVD/CD:
ASUS DRW-24B1ST/BLK/B/AS Black SATA 24X DVD Burner $18.00
OS:
Windows 7 Home Premium 64-bit OEM $100.00
--------------------------
Total: $1,754.00
notes on the i7 SB build:
I like the more powerfull GPU for gaming at 2560x1440.
I like the Noctua Cooler for it superior silent cooling and added clearance over the MB (ram heat spreader)
I like the Bigger PSU just in case I wanted more performance i could put in another GPU in CrossFire (yes, pushing the silent envelope I know)
I like 8GB of ram for less use of the swap file and less wear and tear on the SSD.
I like the faster Sata 6 SSD, would like the OCZ Vertex 3's become available, with 2nd Gen SandForce.