I made a fresh install of ArmA 1.08 and 1.14 patch on this machine:

Macbook Pro Penryn 2.53 GHz
nvidia 8600M 512MB
6 GB 667 RAM
WinXP Pro 32bit

The game runs extremely bad (always under 20 frames).
setting all settings to the lowest options helps for a smoother experience, but this is not acceptable though.

I run on the same Macbook Pro new games like Fallout 3 or Farcry 2 at native resolution (1440x900) in high res textures and very playable fps (above 40 frames).

Whats wrong with my settings?

I remember, ArmA being a hardware hog. What do other Mac user experience in setting up the machine for ArmA?

Settings in game?
Settings in the driver panel?