I'm not as familiar as I should be with NVIDIA cards so go with Toke's advice and get a 670 (or a 7950/7970, better value/performance but not licensed to use PhysX which I know Planetside 2 utilises quite nicely). If you go with an NVIDIA card, you'd be best off with more than 2GB VRAM so get 4GB if possible.
Get 8GB memory if you'll only be doing the standard stuff and gaming. Get 16GB if you'll also be doing heavy video/photo editing (think Photoshop, After Effects, Premiere Pro, Vegas, Avid, et cetera). Whichever you get remember to double up (e.g. 2x4GB or 2x8GB). The processor being an i5 shouldn't have too much bearing on this to my knowledge.
This motherboard has high quality VRM components which the commonly used (including in my own build... oops) ASRock Extreme4 does not.
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If you have a budget and want a whole build that'll be compatible and good value for money feel free to ask