Hi, as posted above and SSD is a wise investment, it will give you the single biggest emprovement in speed and response time of any upgrade. You would notice a big improvement even with your current system. I would go with Intel, Samsung or Crucial as they ( especially Intel ) have the lowest return rates.
If you do decide to upgrade your system the i7-4970k and the Z97 chipset will serve you well. The Z79 chipset has more USB3 and SATA3 inputs that your current system.If your not overclocking your CPU, you could save a few bucks and go for the non "K" version of the CPUs as the only difference is the "K" version has an unlocked multiplier for overclocking. And as above don't skimp on RAM, a minimum of 8GB @ 1600Mhz or higher.
Cheers