help getting fc4 working with dual nics and vpn

[Randy Paries]

hello,
I have a linux box that is running fc4. It has two nics on it.
One Nic has a public IP that is locked down tight with IPtables.
the second nic is connected to a lan with 192.168.0.x ips.

I have a VPN router that has a public IP that also connects to the
192.168.0.x lan.

I am have problems i think with routing.

if my default route on the linux box points to my main router with the
public ip , i can access the linux box via the public IP (if i open up
iptables), but i can not access the linux box via the VPN and the lan
IP.

if i change the default route on this linux box to be the VPN router,
i can connect the linux box via the local ip (when logged into the
VPN) , but can not longer connect to the public ip.

i  think i need to add some route statements, but i am not sure what
and i am not a network guy. This actually may be to much over my head.

ANy help would be appreciated

thanks
randy