Ok, so little over £400, but this is what we've got now:
CPU:
AMD FX4300 Black Edition 4 Core (3.8/4.0GHz, 8MB Level 3 Cache, 4MB Level 2 Cache, Socket AM3+, 95W - £94.49
Motherboard: Asus M5A78L-M/USB3 Motherboard (Socket AM3+, Up to 16GB DDR3 - £55.27
RAM: Corsair CMZ8GX3M2A1600C9 8GB - £34.98
Graphics Card: Sapphire Radeon HD7750 Graphics Card (1GB, GDDR5) - £73.63
DVD Drive: Sony AD-7280S SATA - £13.00
PSU: Corsair CMPSU-500CXV2UK Builder Series CX500V2 - £48.50
Gaming Case: Zalman Z11 Plus Midi Tower Case - £49.99
HDD: Samsung F3 HD103SJ 1TB - £58.87
Total: £428.73, what you think?