[xwiki-users] XEM.war, XEM.war and Plugin Wiki Manager... getting confused

Hi, I'm having a look at virtual wikis and I'm a bit confused with all the installation possibilities. In my understanding, XEM is an easy way to manage several XWiki instances on one server. Starting from a fresh install you would download the XEM.war file into your tomcat, import the XEM.xarfile, and it should work. But what do you do when you already have an instance of xwiki running and you want to add the management capabilities ? Is it when the Wiki Manager plugin comes along ? Am I right in saying : * fresh install : XEM.war and XEM.xar * xwiki already installed (xwiki.war) : use the Wiki Manager plugin and forget about XEM (war and xar) Thnaks, Antonio