It's foolish to buy another i5, when you have already one, and when the lga 1155 doesn't have more cpus coming, the i5 will perform as good as an i5-3570K at stock.
And it has to be a good z77 board with two pcie 3.0 slots dual mode 8x/8x for proper dual crossfire setup, it will cost more than 120$ a motherboard, not to mention the 520 psu won't do for it(two cards).
It's your opinion, but a 7870 does NOT maxout any of the demanding games, for a gaming pc, spending just 200$ of 850$ on a card doesn't make sense, you need a better card.
I listed the two cases, if you read my post, i did mention it was out of stock...
21.5" is fine for 1080p, it's not that small, i bet the op won't notice the difference.
It's just a bad suggestion going with a slow 60GB ssd and a lower card for gaming.
Remember you started all this unjustified criticism, when i just put the parts in the direction to the op.