Calendaring solutions?
 

I'm trying to find a good calendaring solution for a small (~35 users) organization. Shared calendars, free/busy, and resource management would be required features. We're fine on the e-mail front from both a client and server perspective, so ideally it wouldn't try to supplant our current e-mail system.

Does anyone know of an open-source application that fits the bill? We will be working with Windows clients, so a web interface is preferred. (Sunbird/Lightning have some limitations in their free/busy implementation.)

Thanks.

I've been looking at Zimbra for a similar scenario. What did you eventually use?

I left the company before a solution was implemented. Sorry I can't be of more help.