Personally would get Gigabyte GA-B75M-D3H for the same price.
With HDD, since OP already has external HDD, he probably can get away with 120GB SSD.
Kingston RAM seems slightly expensive...
Also, it may worth spending extra to go for 7850 if he can afford slightly more.
I have nothing against Gigabyte, but I don't have much experience with them (although the few I've had were great). I have, however, a lot of experience with ASUS (pretty much always use them) and have never recieved DOA mobos. That said, the Gigabyte board is just as good.
I actually have 15x GA-G31M-S2L and 15x Intel Core 2 Duo E7200 that all still works to this day. But that's about it.
I have several PCs. The one I use atm uses the exact HDD I recommended. I also have an external 1TB HDD, but I wouldn't store any games on it. I'm not sure how well it would work with USB3 (Mine's USB2), but I wouldn't recommend it anyway. And 120GB is not enough for games too, not if you ask me at least. Have a 240GB SSD RAID array in another PC, wouldn't fit my games.
I started out aiming for the 7850, but it was like $50 more if I recall correctly (did the build before work, now I'm home and tired) and it would blow the budget.
Also, I just prefer Kingston RAM tbh. Never had
any problems with them, still have DDR1 HyperX modules that work. Samsung makes good RAM too, though.
Definitely go for the 7850 if you can afford it.
Also, if you can afford it, get the AMD FX-4300 and an AM3+ board. It's a quad-core which is pretty cheap but has good performance and is a great overclocker. I'd choose it over the Pentium.
I agree with you, spirit. But the FX-4300 costs $130, $50 more than the Pentium. So you would have to buy a motherboard for $25-50 if you weren't going to blow the budget.