your cpu won't run on z77 chipset which is built for ivb cpus and is socket-incompatible (lga 1366 with 1366 pins vs lga 1155 with 1155 pins). cpu perf wise, imo it would be kinda side-grade. that rig should hold out till haswell or skylake. oc the cpu with a good cooler, if you can. refer to the overclocking section if you need help with that.
gfx card will be an upgrade with the 7850. 7850 is currently the most powerful card that requires a single pcie power connector and delivers gaming performance better than radeon hd 6950 (previously second fastest single gpu card).
lessee if i can describe different core i7 (mainstream desktop cpus)
core i7 8xx (lga 1156, 1156 pins), compatible with p5x series motherboards from nehalem architecture,
core i7 9xx (lga1366, 1366 pins), compatible with x58 chipset motherboards, nehalem, westmere arch.
core i7 2xxx (lga 1155, 1155 pins), comatible with h6x, p67, z68, z7x mobos, sandy bridge arch.
core i7 38xx, 39xx (lga 2011, 2011 pins), x79 chipset motherboads, sandy bridge arch but extreme/enhanced version
core i7 37xx (lga 1155), ivy bridge, compat. with h6x, p67, z68 (after bios update), z7x mobos.