in this issue of pc advisor, they say if you need to spend over £350 on upgrading, you might aswell shell out for a whole new pc altogether. try building ur own pc and then you can keep some stuff to reuse from ur current pc like the case perhaps and monitor, keyboard, mouse and sound card. all you wanna buy is a motherboard, processor and ram. nomore than £250. so actually its upgrading not just by adding parts, but by replacing parts totally.