http://www.amazon.co.uk/gp/product [...] MS7CNB7K7Q THIS ONE! Don't let anyone tell you any different. The 3570k is a WAYYY better processor than that 4 core AMD. And the GTX 660 graphics card is a 220$ card. That's a pretty obvious decision.
BTW I'd build my own machine or have someone build one for me before I'd buy a PC that's already put together. But, to each his own.
Also the PC I did NOT recommend does NOT come with an operating system. That's gonna cost you an extra 150 bucks and I would not buy from that retailer either as it sounds fishy and gives a fake telephone number it looks like.