My computer has gone super slow, but I've had it for 2 years now..
I got around £150 - £250 ($220 - $370) to spend on computer parts.
My old (current) graphics card is Nvidia GeForce GT 640 and processor AMD FX 4130 Quad-Core.

What parts should I get, so I can play the latest games (Just Cause 3, Blade & Soul, Rainbow Six Siege, etc...) without any lag?

Also, I will be buying parts from UK only (amazon or other UK websites or a store).