Do you happen to have any spare SATA HDDS you can reuse? HDD prices have gone through the roof lately and I think you're going to struggle to meet your expectations at that budget otherwise. Either way you're looking at something along these lines:
Your basket
Product Name Qty Price Line Total
Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor - Retail Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor - Retail £167.99
(£139.99) £167.99
(£139.99)
MSI Z68A-G43-G3 Intel Z68 (Socket 1155) DDR3 Motherboard MSI Z68A-G43-G3 Intel Z68 (Socket 1155) DDR3 Motherboard £94.98
(£79.15) £94.98
(£79.15)
Samsung SpinPoint F3 500GB SATA-II 16MB Cache - OEM (HD502HJ) Samsung SpinPoint F3 500GB SATA-II 16MB Cache - OEM (HD502HJ) £89.99
(£74.99) £89.99
(£74.99)
Corsair Builder Series CX 500W V2 '80 Plus' Power Supply (CMPSU-500CXUKV2) Corsair Builder Series CX 500W V2 '80 Plus' Power Supply (CMPSU-500CXUKV2) £52.99
(£44.16) £52.99
(£44.16)
Cooler Master Elite 430 Windowed Case - Black Cooler Master Elite 430 Windowed Case - Black £39.98
(£33.32) £39.98
(£33.32)
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9) Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9) £23.99
(£19.99) £23.99
(£19.99)
Sub Total : £391.60
Shipping cost assumes delivery to UK Mainland with:
DPD Next Day Parcel
(This can be changed during checkout) Shipping : £11.75
VAT is being charged at 20.00% VAT : £80.67
Total : £484.02
Plus the most powerful graphics card you can afford. The motherboard I suggested has a 20% cashback offer at the moment that you can take advantage of and get some money back:
http://forums.overclockers.co.uk/showthread.php?t=18338613
Obviously if you do have a spare hard drive then you can drop the Samsung F3 and save £90 off the build. If possible try and keep the i5 2500k since it has an unlocked multiplier and overclocks very well with additional cooling (something else you may want to invest in). The case I listed is a nice budget case but there are others available, just take a look. The Elite 430 will probably need at least one extra 120mm exhaust fan however but they can be had for as little as a few quid. Hope this helps, I've tried to keep as close to budget as possible without sacrificing quality.