If your not impressed by a 2500k then you will not be impressed at all by 3770.
Over clock it to 4.5 if you havent already.
If you werent impressed at gaming your last CPU was probably not your bottleneck, get a better video card.
I think your motherboard is fine as long as you have a bios update that supports the 3770.
Your best upgrade in regards to gaming is a video card.