You are let down by a very average graphics card. You do not mention what resolution monitor you want to play these games on which will also have a bearing on the settings, the higher the resolution the lower the settings. Have a look at this excellent review site and it's opinion of the 550 ti. GPU.
Order. that site you linked to is only useful once you have bought the system, I think the OP is asking for an opinion prior to purchase.
Nice PC but awful graphics card. Consider adding an Nvidia GTX560ti for about £170 but then you might have to upgrade the PSU too if it's only rated at 400W.
So, it WILL run the games but quite poorly due to the graphics card.
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