PC upgrade for £300-£400 budget?

Mxhawthy

Distinguished
Looking to build/buy a PC with a £300 - £400 budget (about $500 - $650), (I know it's quite a low budget). I only need SOME parts to upgrade, which I will mention below. Any help is greatly appreciated.

Here is my current PC specs that I would like to upgrade, with links to them on Amazon:

CPU - AMD Athlon X4 750K Quad Core - http://goo.gl/i7fbmZ

Motherboard - Gigabyte F2A55M-DS2 - http://goo.gl/pi9Jq3

Graphics Card - AMD Radeon HD 6670 - http://goo.gl/H2e6uE

Power Supply - 500W ATX Switching Power Supply - That's all I know.

The following are things that I DON'T want to upgrade. I have just included them so you know if your suggestions are compatible with them:

Computer Case - Galaxy 3 Mid Tower ATX Case - http://goo.gl/0Qvm6H

RAM - 16GB ( 2 sticks of 8GB ) DDR3 1600mhz.

Hard Drive - 1 Terabyte SATA drive




Here are some more details:

-------------------------------------

Budget Range: £400 MAXIMUM for upgrades in total.

System Usage from Most to Least Important: Gaming, but quite a lot of internet browsing aswell, and must be able to do word documents, etc for homework.


The parts that I need are: CPU, with a CPU cooler if I need one (I don't know about this sort of stuff), Motherboard, Graphics card, and a Power Supply.


Do I need to buy an Operating System: No

Preferred Website(s) for Parts: www.amazon.co.uk www.novatech.co.uk www.maplin.co.uk www.pcworld.co.uk www.currys.co.uk or basically any reliable UK company selling PC components.

Location: England.

Parts Preferences: I don't really mind.

Overclocking: No.

SLI or Crossfire: Nope.

Some things, such as cooling systems, and compatibility, I am completely clueless about, so could you please make sure you include a cooling system if the CPU that you suggest needs one, and make sure everything is compatible with whichever motherboard you suggest for me. Thanks, and sorry for being a pain.

Additional Comments: I would like it if my PC wasn't ridiculously loud, (although this isn't a HUGE worry) and could play games such as BF4, Far Cry 3, Watchdogs, Titanfall, and Minecraft, all on high settings.
I also need it to be able to surf the web with good speed, and be able to handle spreadsheets, and documents easily.

Any help is very appreciated, as I haven't got a clue where to start.

Thanks for reading