Hi, i would drop the Corsair case because i've heard the cooling isn't great. I think it's meant more for quietness. Personally i'd go for an Antec 902 or 1200 or a HAF 922/933/X, theyre more geared toward cooling. Also you should give Aria a try, heres a build i made on there:
i5 2500k - £163.19
2x4GB Corsair XMS3 1600Mhz - £71.16
Gigabyte GA-Z68MA-D2H -£98.99 (And still has x8/x8 Dual SLI)
XFX Pro 750W - £71.86
HAF 932 - £104.39
1TB Samsung F3 - £40.79
Noctua NH-D14 - £59.99
MSI ATI Radeon HD 6950 Twin FrozR II - £197.99
Windows 7 Home Edition 64 Bit - £70.79
£899.95 With Delivery
Ok i typed that after the first paragraph without realising that Ebuyer is equally cheap as Aria . I would still reccommend a cheaper case and you can still get a cheaper motherboard with x8/x8 capabilities. As for the graphics and cooling, i would reccommend the HD 6950 GB and the Noctua NH-D14 because in my opinion theyre both top quality components with good value for money.
I would choose between the Asrock P67 Extreme4 and the Asus P8P67 Pro. Altho seeing as these are more expensive than that Gigabyte Z68 board that jmsellars mentioned, if the quality, features, layout, etc of that board is sufficient/comparable to those two P67 boards then you might as well just go for that Gigabyte.
The cooler that I would prefer to go for is the Thermalright Archon, which is just as good, if not better than the Noctua NH-D14/Thermalright Silver Arrow, but is usually cheaper. SPCR have compared the Noctua 14cm fan to the Thermalright TY-140 a few times and the Thermalright was shown to be superior. http://www.scan.co.uk/products/thermalright-archon-120-...
It is quite tall, it will fit in any of the cases mentioned so far in this thread, but if you change your mind about the case again then make sure that it can take heatsinks 170mm tall if you want to use the Archon.
A few extra quid gets you a modular PSU:
Adata HM 750W 80Plus Bronze Modular £75 http://www.ebuyer.com/product/261367
With the cases we've been looking at so far a modular PSU is not any sort of necessity, as there would be plenty of room in any of the cases mentioned to store away unused cables.
If budget is not that much of a concern to you then, if I was you, I'd be tempted to get something with even higher quality, something that is known for being quiet, higher efficiency and modular like the Silverstone Strider Plus 750W.