Jamezinho
Golden Boot Winner
For info on AMD processors, check bsmaff's advice a few posts back. Intel CPUs are generally recommended but bsmaff made a good case for AMD chips and which motherboard to get. (posts #1745 & 1754)
As far as GPUs are concerned, around £200 is the sweet spot right now. You should be looking at either a GTX 670 or 760 from Nvidia, or a Radeon HD7950 from AMD. These cards will play most games on max or high settings. There are some great deals on these cards right now. The 7950 is a good choice because it offers 3gb VRAM which makes it a little more future-proof. The Gigabyte Windforce 7950 supposedly has the quietest, most effective cooler.
A PSU of around 550-650W will do fine. Modular is best to keep the mess of cables down to a minimum.
8gb DDR3 RAM will be plenty for gaming. Get low profile if you can.
If you can afford it pick up a SSD, even if it's just a small one to use as a boot drive for Windows. That way you get console fast start-up times. Get a 1-2TB HDD to put your games on.
Definitely get a new card as that will give you the best performance increase for your money. I think you will need to overhaul your system at some point, particularly with next-gen consoles on the horizon.
For £100 you could pick up an AMD Radeon 7790, which is the card the XB1's GPU is based on. However, I would try and increase the budget a little and pick up a 7850 (which is what the PS4 is using). I had one of these and it's a great card.
You can get a 1gb version for around £125 or the 2gb card for around £140. 2gb will be a bit more future proof and will help when playing texture intensive games and mods.
Otherwise wait until October when the AMD releases the 9000 series and see if there are price drops on 7000 series cards. I wouldn't recommend Nvidia at this price point as they don't offer the same value for money as AMD.
Also check your power supply is up to the task of powering a newer card.
