In general a core i3 should not be much of a bottleneck, and going from a LGA 775 based CPU to a LGA 1150 CPU will bring much cooler and quieter operation. Speeds in going from a quad core like the Q6600 to a dual core (hyperthreaded) i3 should be about equivalent, single threaded operations will be much faster, overall performance will be better.
One other big advantage will be upgrading. Should you choose, you can go to a Haswell i5/i7 later on which will be a solid performer for many more years.