"What should I set the anti-aliasing to? Currently it is on the 'automatic' mode so it sorts it out itself. What does AA do exactly?"
I don`t have AA turned on, it`s on automatic, so this means that it`s turned off. With AA your set to 4x and if you have 1024x768 screen resolution, it will look like you have 2048x1536, something like that, but performance droop is much bigger than with just Antistrophic filtering. You should try it, and then you will se, if you can run GP4 still on the same graphic setup. I hope you know, what i mean.
Ferrari is the best!!! (of course it`s not)
We don`t use any programs for changing the Antistrophic filtering. It`s in the gfx card drivers. I see, that you have GeForce, so it`s a bit different than for Radeons. But try this: properties, settings, advance, and then you should see a Geforce FX 5200 or something like that in that advance settings. Then click on this, and you will see the menu on the left, which will probably open. Then searc in that menu for AF or Antistrophic filtering. It should be at Image Qualty or something like that. Then set AF to 4x. I hope that works for you, otherwise you still can ask here in this topic for help.