if i was building today i would use a 3570 cpu and a asus or gigabyte z77 motherboard. in two months time i would wait for haswell cpu to drop. at the time of there dropping i would look to see if there performance is worth the extra cash to buy them.
if not i would start with the ib cpu. the same issue goes for amd and there new 8000 line of gpu when they drop.
I think i will wait then and then ask again in 2 months