Ok, great suggestions above to get that screen shot before making purchases.
Wow, you are out of RAM, my friend.
Look, you know you need to reinstall the OS, you need a new motherboard, you need at least 8GB of RAM, and yes, you should probably have an SSD.
Now, since you're doing all of this, I suggest you just start over with an i3-3220. I just can't recommend you spend money on a new AMD motherboard simply to use your old, somewhat slow cpu again. Seems like a missed opportunity, given how much you're spending and the hassle of rebuilding the whole system from scratch.
Plus, this way, you might be able to repurpose or sell the old system.
If he had a use for the old motherboard cpu and ram or if he feels comfortable selling it then starting over could make sense but going back to a dual core in this use case sounds like a step back. Quad core i5 or a8 5600k would be my recommendation.