We get plenty of people here looking for this type of upgrade with Q6600s or even Core2 Duo setups, and I know neither will come any where close to using the potential of a GTX970, like I said, it's essential to get the specs before making any recommendations.
@ Shaunkay: Yep, the specs look more than OK.
Not for gaming, the i7 4790 doesn't do that much better than the i5 4690, certainly not enough to justify the price premium.