I had a Q6600 Intel quad @ 2.4 GHZ, I have Nvidia 460 GTX, 4GB ram DDR2 667mhz. I was getting 50 - 60 fps on planets with everything full, shadows off. 15 - 25 fps in warzones/raids. I just upgraded to a new Asus P8Z68-VLX Mainboard and i5 2500k and 8 GB DDR3 1333mhz.
I can say i saw a huge improvement. i now get 30 - 60 fps in warzones (average about 40) with shadows on!
I dont know about the 460 GT, i have 460 GTX which is over a year old but fine for this game on full settings.
Get a new CPU and Mainboard. Best way if you can manage.