It shouldn't be too much of a bottleneck. You should be in decent shape but that Phenom would guarantee you a perfect match. If money is an issue I understand, the Athlon should work.
The 7790 and Athlon combo should fare much better. I'm not an expert on Pentiums but I do know the Athlon II is a strong chip. However I would personally see about getting the extra 20$ and getting a Phenom chip.
It shouldn't be too much of a bottleneck. You should be in decent shape but that Phenom would guarantee you a perfect match. If money is an issue I understand, the Athlon should work.