Bottleneck?

First of all do you have the power supply for the 7970? Too often people come here and dont have the right stuff to run high end cards and complain about it not working. Not that you will but you know.

And the G630 will only have a slight bottleneck but I wouldnt be worried. If you want to upgrade your setup you could go with a i3 2100 and get something like a 7870; performance would be more rounded.

I know that psu upgrade would likely be required but I want to make sure that I'm commited to getting the card before making the jump.

It depends on the PSU you have right now. And if you are working with that kind of budget you would see an improvement from an upgraded processor, like the i3 2100 and getting a 7870 or 7850 like I had suggested.

The 7970 will run all modern games today. What games are you trying to run?

Most of the games I play are mostly 3-5 year old games. Nothing new like Max Payne 3. I usually wait for games to become cheaper.

In that case you would probably benefit from something cheaper; the 7970 is going to become overkill for most 3-5 year old games. You could go for it though, and in 3-5 years it would still run games of yesteryear  

How much are you willing to spend? Something like the Radeon 6870 would be a good upgrade from that point.

7970 is on sale with 6 games for $380. I have around $100 in paypal credit, so to me it would end being around $300 actually spent. How much would a 7870 go for or should I wait for the 660 ti? The only game that I can think of that would probably take advantage of the gpu that I would play is GTA IV with the Icenhancer mod.

If you want the games go for the 7970. Maybe if they come with the 7950 you could go with that as well. And thats pretty cheap for a 7970 to begin with.