I'd go something like this, it's £5 over budget but it'd do well for gaming. The CPU isn't the newest but performs well for the price, you get 8GB RAM and a better graphics card. You could get an i5 and a 270X, but this would be more powerful for gaming.
PCPartPicker part list / Price breakdown by merchant
CPU: AMD FX-6300 3.5GHz 6-Core Processor (£77.56 @ Scan.co.uk)
Motherboard: Gigabyte GA-78LMT-USB3 Micro ATX AM3+ Motherboard (£39.59 @ Aria PC)
Memory: Kingston Savage 8GB (1 x 8GB) DDR3-1600 Memory (£45.24 @ CCL Computers)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£38.34 @ Aria PC)
Video Card: XFX Radeon R9 280 3GB Double Dissipation Video Card (£143.99 @ Aria PC)
Case: Cooler Master K280 ATX Mid Tower Case (£21.48 @ Amazon UK)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply (£38.99 @ Novatech)
Total: £405.19
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-05-12 17:24 BST+0100
You're all making me jealous. I'd be maxing out every game I had if I had a PC that good...
