At that Price, it's the king of a budget gaming pc.
Ofc you could pick some better GPUs, but that would sacrifice a lot of Money. So GTX 650 ti might be the choice to make, it's around the same Price as Radeon 7770, and just look at the performance difference of the two GTX 650 ti vs Radeon 7770http://uk.hardware.info/reviews/3233/19/nvidia-geforce-gtx-650-ti-review-gigabyte-vs-msi-vs-zotac-geforce-gtx-650-ti-vs-radeon-hd-7770
GTX 650 ti easily surpasses Radeon 7770, keep in mind that results now might be different because drivers aren't up to date still drivers can't make up for that GTX 650 ti is ahead. http://www.anandtech.com/bench/Product/680?vs=535
Here is a comparison of radeon 7750 vs GTX 650 ti.
The Price should be around 110-120$, it should make a significant difference.
Hope this helps, good luck!