The GTX 260, although a "last generation" card, is by no means "outdated" for 1680x1050 resolutions. At least not in my opinion. It's a perfectly fine card.
However, I do agree with the sentiments with regard to your CPU. The original Phenom series wasn't all that great.
To see whether your CPU is really your limitation, I'd suggest lowering your resolution setting or other graphic settings. See if you gain FPS. If you see no gains, then you know the GPU isn't the limiting factor (in that case it's likely CPU).
Also keep in mind, with MMO type games, latency issues can also cause performance problems locally.