I would be much more concerned with your processor and amount of RAM to begin with, let alone a graphics card. If you're on a budget the best route to go is AMD; likely your best bet would be a Phenom II X4, the 3.0Ghz is only 125$ and you can grab a cheap and reliable Asus motherboard for less. 4Gb of RAM nowadays is only around 30 - 40$ as well (which is more or less the baseline currently). I'd imagine that would total around 250 - 300$, at which point you can go for a graphics card, with a GTX 460 putting you in a good spot for a while to come and only costing around 150ish. I chose the Nvidia route for graphics because their drivers are generally much better and better optimized than you'd find in ATI cards at the same price point -- though, I may just be partially bias. All-in-all, your "rig" definitely needs some work, and you don't have to spend a fortune to play SWTOR, just enough to be at standard.