Client/Server Calendar Program?

Dethnyte asks: "At my office, we currently use Calendar Creator Pro, it's just not a very good or user-friendly program for multiple people entering data into a calendar. We don't want to use Outlook or anything that requires a server, or at least a server program we have to pay for. Is there anything Open Source that can help us out? We'd use Sunbird, but it still has too many bugs. We need something simple that can keep dates, multiple schedules, and still be readable when printed out."