RAS PPTP problem with WS2003 with 2 NICs

Hi,

I hope you can help me. I have the following situation:

We have an application /web server (w2003 enterprise) and a db server
(w2003 enterprise). The two are connected through an internal network
with address range 10.0.0.*. The application / web server has a second
nic with a public ip address (212.10.*.*) for internet access. The
servers stand behind a firewall (netscreen 500 if i am correct). We
would like to be able to connect to the application / web server
through a VPN on the external nic (212.10.*.*). Through this VPN
connection we would like to be able to connect to the internal network
(10.0.0.*) to access the other server. The problem rises when we try to
install the RAS. It will only show 128 L2TP ports and the PPoE port
(129 in total) and not the PPTP ports. Our firewall is set up to
transfer the PPTP port (with GRE protocol number 47), so this is what
we need on the RAS server to be enabled. Trying to put the L2TP ports
to 0 and the PPTP ports to 1000 in the configuration still does not
show the PPTP VPN ports. How can we solve this? I have read a few
articles on DNS issues and pointing all DNS server to the internal nic
etc... but this seems a bit weird on a webserver that needs the
external interface to for instance send mails.. The DNS servers we use
are the ones in the 212.10.*.* range that the provider put in there.

Hope somebody can help.
Alexander