[turtle]

Since you don't have anything other than iPhoto to make your corrections with, I would suggest you limit yourself to shooting with Large-Fine JPG and master your WB settings. Then you will have the room to make small adjustments. iPhoto is good, but can only adjust so far. With PS, I just set the white point to one of the highlights in that image. Obviously this won't be true to the scene when you took the image, but it's surely much closer than the RAW data. If you are still planning to shoot with RAW though, then shoot with RAW + JPG. Then you can modify the RAW data later, when you have the software to do it, and you'll have the JPG to work with in the mean time.

Trust me, this will really help you to learn your cameras WB settings. This is also where the grey card would com in handy by allowing you to set the custom WB when in such horrid lighting conditions.