Motherboard is one of the more important components. It needs to have reliable components since everything else in your system communicates through it.
The 3570k is not only slightly faster but has an unlocked multiplier, which means you can over clock it in the future if you want to. If you're looking for a place to put the extra $30, this isn't a bad place, IMO, since over locking is an easy way to make a system last longer.
With that, I recommend this combo:
3570k +
ASRock mobo