New Computer Build

For gaming, an i7 is overkill.

PCPartPicker part list: http://uk.pcpartpicker.com/p/DWrY
Price breakdown by merchant: http://uk.pcpartpicker.com/p/DWrY/by_merchant/
Benchmarks: http://uk.pcpartpicker.com/p/DWrY/benchmarks/

CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor (£155.99 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£24.99 @ Amazon UK)
Motherboard: ASRock Z77 Extreme4 ATX LGA1155 Motherboard (£101.98 @ Dabs)
Memory: Corsair XMS3 8GB (2 x 4GB) DDR3-1600 Memory (£32.99 @ Amazon UK)
Storage: Crucial M4 128GB 2.5" Solid State Disk (£80.54 @ Scan.co.uk)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£50.32 @ Ebuyer)
Video Card: Sapphire Radeon HD 7970 GHz Edition 3GB Video Card (2-Way CrossFire) (£342.40 @ Amazon UK)
Video Card: Sapphire Radeon HD 7970 GHz Edition 3GB Video Card (2-Way CrossFire) (£342.40 @ Amazon UK)
Case: Cooler Master HAF XM (Black) ATX Mid Tower Case (£94.99 @ Amazon UK)
Power Supply: XFX ProSeries 850W 80 PLUS Silver Certified ATX12V / EPS12V Power Supply (£99.98 @ Overclockers.co.uk)
Optical Drive: Asus BC-12B1ST/BLK/B/AS Blu-Ray Reader, DVD/CD Writer (£47.12 @ CCL Computers)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) (£65.99 @ Aria PC)
Total: £1439.69
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-16 22:05 GMT+0000)

Get rid of the i7, don't crossfire, get the single best card you can afford. Other than that, all seems fine I guess, be nice to have the links.

Firstly you don't have to go with a couple items I've listed. The ghz edition cards are just extra if you want just standard 7970's you can save a little there and be just fine. Also, I went with the Noctua cooler because they make amazing coolers and fans. And where you can go with something like the Cooler Master product paying 1500 euro on a computer you can afford to put a little more into your cooling in other words a "Proper" cooler. I also changed your ram I went with vengeance ram and since the 1866 ram was at a good price and is low profile I thought why not. Furthermore. I changed the SSD because if you are going to get a SSD please get the premium SSD's they are primed to be more strengthened for more heavy writing and durability over time. And that Samsung 830 is enough to put your OS on it and then you can put a program or two then toss the rest on your Hard Drive. Also, I like the Fractal Design Define R4 because its built with silence in mind but also has great cooling and is easy to build int. With that being said Cases are a personal statement so if you like the case you have listed above go for it.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor (£155.99 @ Aria PC)
CPU Cooler: Noctua NH-D14 65.0 CFM CPU Cooler (£55.88 @ Ebuyer)
Motherboard: ASRock Z77 Extreme4 ATX LGA1155 Motherboard (£101.98 @ Dabs)
Memory: Corsair Vengeance LP 8GB (2 x 4GB) DDR3-1866 Memory (£44.99 @ Amazon UK)
Storage: Western Digital Caviar Black 1TB 3.5" 7200RPM Internal Hard Drive (£69.29 @ Amazon UK)
Storage: Samsung 830 Series 64GB 2.5" Solid State Disk (£55.00 @ Amazon UK)
Video Card: Sapphire Radeon HD 7970 GHz Edition 3GB Video Card (2-Way CrossFire) (£342.40 @ Amazon UK)
Video Card: Sapphire Radeon HD 7970 GHz Edition 3GB Video Card (2-Way CrossFire) (£342.40 @ Amazon UK)
Case: Fractal Design Define R4 (Black Pearl) ATX Mid Tower Case (£78.95 @ Aria PC)
Power Supply: XFX 850W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply (£88.74 @ Aria PC)
Optical Drive: Asus BW-12B1ST/BLK/G/AS Blu-Ray/DVD/CD Writer (£76.00 @ Amazon UK)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) (£65.99 @ Aria PC)
Total: £1477.61
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-17 07:33 GMT+0000)

If you've got the budget why not? Dual 670s = GTX 690. Dual 7970 would be better still.

The above builds are good but I wouldn't bother with BD-R on PC. It's expensive (playback software costs an extra $100 a license) and doesn't always work when you want it to.

Here's what I would suggest:

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor (£155.99 @ Aria PC)
CPU Cooler: Noctua NH-D14 65.0 CFM CPU Cooler (£55.88 @ Ebuyer)
Motherboard: Gigabyte GA-Z77X-UP4 TH ATX LGA1155 Motherboard (£139.99 @ Aria PC)
Memory: Mushkin Blackline 8GB (2 x 4GB) DDR3-1600 Memory (£41.99 @ Aria PC)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£52.00 @ Amazon UK)
Storage: OCZ Vector Series 128GB 2.5" Solid State Disk (£101.99 @ Ebuyer)
Video Card: Gigabyte GeForce GTX 670 2GB Video Card (2-Way SLI) (£299.99 @ Amazon UK)
Video Card: Gigabyte GeForce GTX 670 2GB Video Card (2-Way SLI) (£299.99 @ Amazon UK)
Case: NZXT Switch 810 (White) ATX Full Tower Case (£159.98 @ Novatech)
Power Supply: NZXT HALE 90 750W 80 PLUS Gold Certified ATX12V / EPS12V Power Supply (£124.99 @ Overclockers.co.uk)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer (£12.98 @ Scan.co.uk)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) (£65.99 @ Aria PC)
Total: £1511.76
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-17 07:45 GMT+0000)

I agree blu ray software is very pricey. And you will want to take that into consideration I use PowerDVD its the best software I have seen for it. And I also have a blu ray drive and I watch blu rays quite frequently on my computer. Also, keep in mind his budget and he was asking for 2 7970's  

Sorry about not putting links. But would you say that 16GB of ram is overkil and just go for 8 instead? And would a 750w PSU be enough to power it all?

For a 7970 crossfire configuration I would go with something like a 850 watt to be safe but im sure if you had a quality 750 watt psu you could be okay sure.