Here's two specs, one with radeon GPU, one with Nvidea, that way you can get which ever you prefer.
Radeon
PCPartPicker part list:
http://pcpartpicker.com/uk/p/y3gH
Price breakdown by merchant: http://pcpartpicker.com/uk/p/y3gH/by_merchant/
Benchmarks: http://pcpartpicker.com/uk/p/y3gH/benchmarks/
CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor (£161.99 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£25.45 @ Scan.co.uk)
Motherboard: Asus P8Z77-V DELUXE ATX LGA1155 Motherboard (£178.21 @ Dabs)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory (£37.98 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£52.74 @ CCL Computers)
Storage: Crucial M4 128GB 2.5" Solid State Disk (£78.96 @ Dabs)
Video Card: XFX Radeon HD 7970 GHz Edition 3GB Video Card (£318.95 @ Scan.co.uk)
Case: BitFenix Colossus ATX Full Tower Case (£95.98 @ Scan.co.uk)
Power Supply: XFX 650W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply (£72.78 @ Scan.co.uk)
Optical Drive: Samsung SN-208DB/BEBE DVD/CD Writer (£17.99 @ Overclockers.co.uk)
Total: £1041.03
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-01-17 11:53 GMT+0000)
Nvidea
PCPartPicker part list:
http://pcpartpicker.com/uk/p/y3sM
Price breakdown by merchant: http://pcpartpicker.com/uk/p/y3sM/by_merchant/
Benchmarks: http://pcpartpicker.com/uk/p/y3sM/benchmarks/
CPU: Intel Core i5-3570K 3.4GHz Quad-Core Processor (£161.99 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£25.45 @ Scan.co.uk)
Motherboard: Asus P8Z77-V DELUXE ATX LGA1155 Motherboard (£178.21 @ Dabs)
Memory: Corsair Vengeance 8GB (2 x 4GB) DDR3-1600 Memory (£37.98 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£52.74 @ CCL Computers)
Storage: Crucial M4 128GB 2.5" Solid State Disk (£78.96 @ Dabs)
Video Card: EVGA GeForce GTX 680 2GB Video Card (£359.62 @ Scan.co.uk)
Case: BitFenix Colossus ATX Full Tower Case (£95.98 @ Scan.co.uk)
Power Supply: XFX 650W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply (£72.78 @ Scan.co.uk)
Optical Drive: Samsung SN-208DB/BEBE DVD/CD Writer (£17.99 @ Overclockers.co.uk)
Total: £1081.70
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-01-17 13:01 GMT+0000)