Since all new macs come with IE installed, they will also include the 'core' MS fonts installed from the factory... even if the end user throws away IE, I've never heard of anyone purging their fonts folder of the accompanying fonts. Many older macs will also have at least one MS program on them... Word, IE, etc., or at least one graphics program (which often include a full complement of 'standard' fonts).
Short answer: YES
EDIT: If you are asking this because you want to code a webpage that has fonts viewable on both Win & Macs, you can embed the font for the 'just in case' circumstances. Help on embedded fonts can be found at WebMonkey.com
__________________ Davy - Programming since 1998 [CV] Currently working on: n/a Status: n/a