I've installed zabbix following the how to, on debian sarge with ispconfig installed. I've added the the lines to my apache2.conf to allow it be accessible from domain/~zabbix but all it does is show the PHP code. I haven't been able to figure out how to get it to allow the php script to run from that directory... Bit of a newbie question
I guess you followed one of the "Perfect Setup" guides from HowtoForge. In these guides PHP is disabled globally because in ISPConfig you want to be able to enable PHP on a per-site basis. Now you created a web site manually for Zabbix, and that's why PHP doesn't work there. Please create a web site for Zabbix with ISPConfig and enable PHP for that web site, and then install Zabbix in that web site.