To make a long story short I basically have a new Imac that is useless for photography. The brightness level cannot be turned down under 226 making it impossible to calibrate correctly. I understand some might not have this problem, however searching the 24" IMAC's I have found this issue posted in quite a few places.
Keep this in mind before purchasing one. OH and BTW it's not the brand new one, it's about 2 months old...........that's how long it took me to figure out this problem.