Your CPU & RAM are more than good enough for SWTOR even on maximum settings and I believe, as you suspect, that the problem lies with your Graphics Card, depending on your budget something like a GTX560 will play SWTOR relativley smoothly even on high resolutions that your 23 inch LED is capable of (around 1920x1080)however this will require a minimum of a 450w power suply unit and I recommend getting something like a 600 watt or 650 watt to future proof yourself a little-bit if you wanted to upgrade Graphics again in the future as all the newer cards are demanding more and more power.