I guess the first questions are to frame the amount of horsepower and level of quiet you need:
- Was the i7-960 running at 100% load or did it have some headroom with your apps? If there was a good bit of headroom, then the i5 should be good enough. If not, there's the i7. Wander the Anandtech Bench
to see the differences.
- Do you consider your MSI GTX 680 quiet enough for your uses?
Take a look at SPCR's review
of Puget Systems' P183 V3 Serenity build to get a feel for what you can aim for. If you want Antec, the P183 V3 is a good choice. If you want a smaller case, the Solo II is a very quiet case. I like the Fractal Design Define R4 - see my signature for a recent build thread.
Mobo - Haswell uses Socket 1150. So, it'll be a Z87 series motherboard.