The Story: (You can skip it if you want, but there's some technical stuff in it too)
Recently I received a small amount of cash ($535) and I made a deal, in wich I traded a microSD card of 8gb for a desktop (LOL). Well, when I removed the cover to see If I had made a good deal or not, I found myself with:
Changes: Switched from amd to intel i5, i5 is proven to be best cpu you would need for gaming, just threw in any random motherboard that seemed good (could possibly cut down on this do to lack of need for overclocking).
The 7850 is a good match for the i5 and is significantly better than the 7770.
I have a preference to antec, their products have simply worked for me.
You can shop around for an even cheaper motherboard with the features you want like a B75 motherboard. Just make sure it has 4 memory slot if you decide to go with 4GB (2 x 2GB) initially and want to add more later.
Were you able to salvage the optical drive from that older build? Or did it even have one? If so, then you can use that instead of having to buy a new one.
This is what I would get. It'll easily get you ultra settings at comfortable frame rates. This build also offers an amazing upgrade path. Once you've acquired the funds, you can easily swap out the i3 3220 for a far more powerful i5 3570k chip. Or if you're needs demand it, you can get the i7 3770k.