This is only thing I'd recomend really tbh, £357.95
Asus ATI Radeon HD 5770 1024MB GDDR5 PCI-Express Graphics Card + Colin McRae Dirt 2 Full Game + Ruby Doll £119.98 (£104.33)
AMD Phenom II X3 Tri Core 720 Black Edition 2.80GHz (Socket AM3) - Retail £97.99 (£85.21)
OCZ Platinum 4GB (2x2GB) DDR3 PC3-10666C7 1333MHz Dual Channel (OCZ3P13334GK) £70.99 (£61.73)
Asus M4A77TD Pro AMD 770 (Socket AM3) PCI-Express DDR3 Motherboard £68.99 (£59.99)
You could swap the cpu out for an athlon quad, but assuming youre gonna use it for gaming this is probably better, could spec for £300 but you're gonna lose on both cpu and gfx (prob a dual core and 4850/4870)