Hmm, things seems OK but I'd suggest you go for the 3570k as you can overclock when doing vid/aud editing. And don't take that B75, it's for business use. Go for the Z77, and choose a better brand like ASUS or Gigabyte.
Asus and Gigabyte are not better brands than ASRock. The're all on-par with some good boards, some great boards, and some bad boards. Even worse, many of Gigabyte's and Asus' lower end boards are unreliable whereas ASRock has much more consistently good quality among their lower end boards.
The chipset would mostly matter just for having extra features with the IGP and for overclocking a K edition i5 or i7. If you don't get a K edition, then there's a lot less incentive to get an expensive motherboard. Being for business use doesn't matter, a B75 board could work just fine for a gaming system's motherboard. Even Tom's own system builders for the SBMs have done one or two gaming systems with B75 boards and recommend them.