I am searching for a calendar system that will support:

1. Access to the calendar from my local system
2. Access to the calendar via the Internet
3. Provide multi-user support so we may share calendars via the Internet
4. Preferably would sync with Google, Outlook, and/or PDA
5. Somewhat inexpensive as this is for a small business with less than ten employees

I found something called Cozi Central that handles 1,2,3, and 5, but it is family-oriented software, not business. It is hard for me to believe there is NOTHING out there except expensive enterprise solutions. Does anyone have any recommendations?