for the machine its self, I'd go for something like this,
Case
COOLERMASTER CM STORM TROOPER - GAMING ENTHUSIAST CASE
Processor (CPU)
Intel® Core™i7 Quad Core Processor i7-3770K (3.5GHz) 8MB Cache
Motherboard
ASUS® P8Z77-V: PCI-E 3.0 READY, WIFI, SLI, CROSSFIREX
Memory (RAM)
8GB KINGSTON HYPER-X GENESIS DUAL-DDR3 1600MHz, X.M.P (2 x 4GB KIT)
Graphics Card
2GB NVIDIA GEFORCE GTX 680 - 2 DVI, HDMI, DP - 3D Vision Ready
Memory - 1st Hard Disk
120GB KINGSTON HYPERX 3K SSD, SATA 6 Gb/s (upto 555MB/sR | 510MB/sW)
2nd Hard Disk
2TB WD CAVIAR BLACK WD2002FAEX, SATA 6 Gb/s, 64MB CACHE (7200rpm)
1st DVD/BLU-RAY Drive
24x DUAL LAYER DVD WRITER ±R/±RW/RAM
Memory Card Reader
INTERNAL 52 IN 1 CARD READER (XD, MS, CF, SD, etc) + 1 x USB 2.0 PORT
Power Supply
CORSAIR 1050W PRO SERIES™ HX1050-80 PLUS® SILVER MODULAR (£159)
Processor Cooling
SPIRE THERMAX ECLIPSE II UNIVERSAL DT EXTREME CPU COOLER (£39)
Sound Card
ONBOARD 6 CHANNEL (5.1) HIGH DEF AUDIO (AS STANDARD)
Network Facilities
10/100/1000 GIGABIT LAN PORT - AS STANDARD ON ALL PCs
USB Options
6 x USB 2.0 PORTS @ BACK PANEL (MIN 2 FRONT PORTS) AS STANDARD
Operating System
Genuine Windows 7 Home Premium 64 Bit - inc DVD & Licence (£79)
Office Software
NO OFFICE SOFTWARE
Anti-Virus
NO ANTI-VIRUS SOFTWARE
Warranty
3 Year Silver Warranty (1 Year Collect & Return, 1 Year Parts, 3 Year Labour) (£5)
Delivery
STANDARD INSURED DELIVERY TO UK MAINLAND (MON-FRI)
Build Time
Standard Build - Approximately 10 to 12 working days
Quantity
1
well a single 680 is gonna be a right beast, and to be honest ya dont really need two 680's for one screen, although if you wanted to have three screens then yeah would be a good idea.
But, its your rig, so you want dual 680's for massive frames per seconds and gaming performance then you go for it!