Calendar Program Needed!

Hi all! I work for a small consulting firm that specializes in events and fundraising/development consulting. We are searching for a great Calendar program that will allow us to manage all of our events on one calendar, while also allowing us to split them out seperately to bring to client meetings, etc. Calendar Creator for PCs would be perfect, but they don't make a compatible version for macs. Also any program that works for theatres and season planning would be quite applicable. Any great programs to recommend? Thanks much! kford@lizpageassociates.com