i5 4670K + bad motherboard or AMD 8320 + good motherboard?

Those are actually not bad motherboards. Both motherboards are actually very good. Quiet expensive. You can probably live with a Gigabyte GA-Z97X-Gaming 3 for $130.

Other than that, if your PSU is 430W, I would advice the Intel route because AMD processors use more power and with that PSU, I would try to keep the power consumption low so you're not blowing it up. That said, you probably won't be overclocking much on it so buying all the overclockable parts is probably not the best bang for your buck.

You could get an i5 4440 and an H87 board and it would widdle all over that A.M.D. settup in games.
You dont NEED overclocking chips and boards. Bangs per buck goes down, not up with that gear.

You will need to look about for a crossfire H87 or B85 board, Asus H87's only run xfire in x4 mode on the second card. Better to get one decent card for a budget build. Sell the old one. .
Having said that a 660 is not too shabby!

In terms of gaming, the i5 is much stronger than the FX-8320. The FX may have more cores, but each individual core is weaker compared to i5's. And most games do not use many threads so the extra cores that the FX comes in do not play a major role in gaming.

@geofelt meant to say this: http://www.microcenter.com/site/brands/intel-processor-bundles.aspx

I would not trust M.S.I. to build a calculator.

Locked means that it cannot be overclocked. If you do not plan on overclocking, then you don't need to spend extra money on overclocking components because they are a bit more expensive. Obviously you should plan it out with your budget. College is a tough time so I personally don't see a huge advantage in getting an overclockable computer especially if you're not upgrading the GPU or PSU anytime soon. So for now, I would save the money. That said, the bundles in Microcenter is great. Just because you get a deal for an overclockable CPU, it doesn't mean you have to overclock it.

Today, I would buy any Z97 based motherboard. The chipset is newer and provides a future upgrade to broadwell 14nm. They usually do not cost any more than the previous z87 motherboards.

Z97 allows you to overclock a unlocked Intel cpu.
You normally pay 5% more for a 4670K vs. an unlocked 4670. In return, you get overclocked performance conservatively 20% better. A good deal if your budget permits.

Here is my canned rant on planning for dual cards:
-----------------------------Start of rant----------------------------------------------------
Dual graphics cards vs. a good single card.

a) How good do you really need to be?
A single GTX650/ti or 7770 can give you good performance at 1920 x 1200 in most games.

A single GTX660 or 7850 will give you excellent performance at 1920 x 1200 in most games.
Even 2560 x 1600 will be good with lowered detail.
A single gtx690,7990, GTX780ti or R9-290X is about as good as it gets for a single card.

Only if you are looking at triple monitor gaming, or a 4k monitor, might sli/cf will be needed.
Even that is now changing with triple monitor support on top end cards and stronger single card solutions.

b) The costs for a single card are lower.
You require a less expensive motherboard; no need for sli/cf or multiple pci-e slots.
Even a ITX motherboard will do.

Your psu costs are less.
A GTX660 needs a 430w psu, even a GTX780 only needs a 575w psu.
When you add another card to the mix, plan on adding 200w to your psu requirements.

Even the most power hungry GTX690 only needs 620w, or a 7990 needs 700w.

Case cooling becomes more of an issue with dual cards.
That means a more expensive case with more and stronger fans.
You will also look at more noise.

c) Dual gpu's do not always render their half of the display in sync, causing microstuttering. It is an annoying effect.
The benefit of higher benchmark fps can be offset, particularly with lower tier cards.
Read this: http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995.html

d) dual gpu support is dependent on the driver. Not all games can benefit from dual cards.

e) dual cards up front reduces your option to get another card for an upgrade. Not that I suggest you plan for that.
It will often be the case that replacing your current card with a newer gen card will offer a better upgrade path.
The high end Maxwell and amd 8000 or 9000 series are due the end of the year or next year.
-------------------------------End of rant-----------------------------------------------------------

The problem with overclocking is that it could be a problem with that 430W PSU that also powers a GTX 660. It's more than capable of doing that, but overclocking is an area I wouldn't get into for now. It's a tad better on Intel but with AMD, that can spell bad news.

Get that bundle (last one on the page, first option) on Microcenter. It's a great deal and both the CPU and motherboard are overclockable. You don't have to overclock now, but it's there should you want to later. I also recommend an aftermarket cpu cooler for overclocking. The stock one is crap for overclocking. A Cooler Master Hyper 212 EVO is a great deal.