You can certainly run a gaming rig on a 6-core CPU, but it is a waste.
Think of it like this: a game is using 4-cores, on an x6 that means 2 cores are just sitting there idle.
The FX-4100 is faster per core than the FX-6100, so instead of using 4 slower cores and having 2 idle you get more speed and no waste.
You also save $60 to put toward a better graphics card.
Can't really suggest a card until you know how much fat you can cut out of the budget.
$10 from the RAM, +$60 if you go with the FX-4100, +$40 if you can convince him to get Win7 Home.
Thats $110, if you get the M5A99X EVO
MB thats another $35.
$200 for the original card +$145 and you're looking at a GTX 570 or HD 6970.
Please read through the thread thoroughly before responding.
Nobody wants to read a wall of text, formatting is your friend.
i5 3570k | 8GB G.Skill 1600MHz | R9 290 | SeaSonic 750X