Most people do not know about routing. One of the basic needs for this server in a small environment is to use this single Server to be an Internet gateway (Internet connection sharing, if you want to cal it that way).
It would be relative painless to add a config option to identify the Internet interface and the local interface than setup the correct settings for the following in the preferred firewall. I say this because the setup proposed by ISPconfig disables the native firewall like Shorewall on Mandriva and whateverfirewall on others, only to install its own brand Bastille-firewall witch I presume is fine.
The only settings inside bastille-firewall that need to be manages is the Prerouting DNAT and outside the /etc/sysctl.conf = net.ipv4.ip_forward=1
Will make life extremely better for users as I see numerous routing questions on the forums.
O-yeh, what an Awsome Solution this, combinded with the Perfect setup of your choice, is for anyone that does not fall in the LUNITIX category!