They have an SSD benchmark from playing Rift with a SSD vs HDD and it does show a good increase in load times and start up time. I'd imagine SWTOR would do the same. I was in your shoes about 6months ago when I went to my build in my sig. MMORPGs require a lot of cpu support and it looks like you cpu is the e8400 which is what I had :P Even overclocked it still made online gaming difficult.
I initially got my SSD for christmas thinking it would help and it did make things feel faster but as far as gameplay it does nothing. So, I ended up just building a new pc when sandy bridge came out when they fixed the SATA issue.
TL;DR: You'd benefit the most by upgrading the system but if you can't afford it the SSD will at least help you on the load times but you'll still suffer in gameplay.