If you deploy Java WebStart (JNLP), add the following entries to the apache httpd.conf

AddType application/x-java-jnlp-file .jnlp
AddType application/x-java-archive .jar
AddType application/x-java-archive-diff .jardiff

Apache will then send the correct mime-type to the browser and therefore Java will be started when the jnlp file is clicked on.