Do you mean the Q9650? There's no such thing as a Q9560 
Since they both have the same clock speed of 3.0 Ghz, the Q9650 will only give you a marginal improvement over the E5700 due to the fact that it can push the background processes to the extra cores. This means that in Dolphin you'll see an improvement of around 5 fps.
Try those games that you mentioned on the system as-is. If they run fine using the latest dev build or the 5.0-rc builds (which I think they should), then unless the Q9650 is really cheap, I wouldn't upgrade.
Since they both have the same clock speed of 3.0 Ghz, the Q9650 will only give you a marginal improvement over the E5700 due to the fact that it can push the background processes to the extra cores. This means that in Dolphin you'll see an improvement of around 5 fps.
Try those games that you mentioned on the system as-is. If they run fine using the latest dev build or the 5.0-rc builds (which I think they should), then unless the Q9650 is really cheap, I wouldn't upgrade.