well here.
PCPartPicker part list:
http://pcpartpicker.com/p/AhQF
Price breakdown by merchant: http://pcpartpicker.com/p/AhQF/by_merchant/
Benchmarks: http://pcpartpicker.com/p/AhQF/benchmarks/
CPU: Intel Core i5-3470 3.2GHz Quad-Core Processor (£142.20 @ Aria PC)
Motherboard: Gigabyte GA-B75M-D3V Micro ATX LGA1155 Motherboard (£47.70 @ Aria PC)
Memory: Corsair XMS3 8GB (2 x 4GB) DDR3-1600 Memory (£32.99 @ Amazon UK)
Storage: Seagate Constellation ES 1TB 3.5" 7200RPM Internal Hard Drive (£43.82 @ Aria PC)
Video Card: XFX Radeon HD 7870 2GB Video Card (£167.99 @ Aria PC)
Case: Silverstone SST-RL01B-USB 3.0 (Black) ATX Mid Tower Case (£35.16 @ Scan.co.uk)
Power Supply: XFX ProSeries 450W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply (£36.98 @ Novatech)
Total: £506.84
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-01-29 17:32 GMT+0000)
its about 50 quids more, but def worth it for future proofing. ull be fine with 2cores for now but future games will work better with the 4core.