I have a small business with 4 computers (Windows). Each secretary has email contacts. I want to be able to share those email contacts with the 4 computers.

My first try was EssentialPIM but the software is full of bugs.

I was told: MS Exchange... but it requires Windows Server and is awfully expensive. So I answered: I need a free solution.

I was told that to share contacts I need a “groupware”. So I started to create a list of those possible solutions:
* Spicebird http://www.spicebird.com/
* Cyn.in http://www.cynapse.com/cynin
* LibreSource http://dev.libresource.org/ (Java/PostgreSQL)
* eGroupWare http://www.egroupware.org/ (PHP)
* Turba http://www.horde.org/turba/ (PHP)
* Group-Office http://www.group-office.com/ (PHP)
* phpGroupware http://www.phpgroupware.org/ (PHP)
* Simple Groupware http://www.simple-groupware.de/cms/ (PHP)
* collabtive http://collabtive.o-dyn.de/ (PHP)
* tine20 http://www.tine20.org/ (PHP)

Now I don't know which one to use. Has any of you tried one of those? Anyone can recommand what would be best for me (shared contacts for 4 Windows computers)?

Thank you!

ps : for privacy reasons, I do not want my contacts to be shared on a distant server (like Google).