My Mac has a Nvidia 7300 (or Nvidia 7600) series card and the game defaults to the minimum resolution and settings why?

Bioshock is a very graphically intense game and the Nvidia 7000 series cards do not offer the performance levels found on newer graphics cards, to allow you to play the game on this card you will need to play at these lowered settings. Graphics driver development is always ongoing process and we hope that some more performance can be gained on this card via future OS updates.