A new GPU would likely help, since your CPU is capable of pushing playable frame rates. The Nvidia 7800 series is about 6 years old, and would barely make SWTOR playable even at the lowest settings. The AMD 7800 series, on the other hand, would make your CPU a bottleneck. If you have a 300W power supply, an AMD 7750 is a decent option, and should run SWTOR fluently on low-med settings depending on your resolution.