An alternative selection of parts.
Mobo: GA-Z68P-DS3 - £75.22 LN41414
RAM: 4gb 1600mhz DDR3 - £24.48 LN37493
SSD: OCZ 60GB Vertex 2E - £82.32 LN33702
HDD: 1 x 500GB - £31.43 LN28751
PSU: EZcool 500W - £25.67 LN8039
GPU: XFX HD 6870 £137.62 LN37721
CASE: Coolermaster Elite 430 £38.38 LN34936
CD/DVD: SATA DVDRW £13.99 LN39605
Which comes to about £624.32 with postage.
The LN numbers you can just put in the search bar at Scan Computing.
I think having 1 large Hard-drive is asking for trouble as if it fails you could loose everything, so I would suggest splitting the 2TB to 2 x 1TB. you certainly do not need a 700W PSU for your selection a decent 500W will be plenty.
Quad or hex core? you will be unlikely to use the full 6 cores so little point in buying one,so it would be like paying for a car with 6 wheels when 4 would do you just fine.
You do not mention your OS and whether you need to buy that and will it be 64BIT otherwise there is no point in 8GB RAM.
I have also included an SSD in my build but that can easily be swapped for another Sata HDD.