Iptables and RH9

I'm attempting to setup some IP forwarding using iptables. I have used
many scripts already setup just needed to plug my data in. My goal is
to setup forward so that I can use an internal VPN server (Win 2K
Server) I have setup the ports needed in the scripts but it doesnt
seem its getting through. I was play with Xinetd and found that I
could forward ports to another server using the webmin interface. That
seem to forward some ports but its not forwarding the GRE protocol
properly so authentication is not taking place.

Why hasnt iptables worked correctly. I can open and close ports but I
can't forward them.

If possible can I use Xinetd to foward the GRE protocol? I can forward
TCP 1723.

I have the most up to date fixes/kernel according to the Red Hat site.

I'm new to linux and still learning I think I'm miissing a simple
setting.

Thanks for your help!