On Freitag, 1. Juni 2007, you wrote:

OK, I would install a newer version then, which one do you recommend me to install?

Do I have to uninstall the old one or just make an update?

The latest stable version 1.2.1 should be fine. Look at the migration notes in the wiki for update hints, http://openser.org/dokuwiki/doku.php

As you going from 1.0 to 1.2, a complete new installation would be probably easier. So uninstall the old openser, backup your database tables, install the new and migrate the data to the new installation. You find informations about the necessary changes in the mentioned documents.

Henning

P.S: please CC at the user list