Port Forwarding Problem

I need to have incoming access to my computer for games, applications and such. My network is set up at home so that the cable modem is connected to the main computer through a router/firewall, and i am connected to the main computer through a phoneline network. So basically there are two networks, ethernet and phoneline, and the link between them is the main computer, which is connected to both. It has two different ip adressess one for each network.

I configured the router to forward a port to the ip of the main computer and that works fine, however i couldnt figure out how to forward a port to the second computer.

I tried to give the router the ip of the second computer on the phoneline network and that didnt work, i guess because its not on the same network as it.

Anybody know how to do this?

(my main computer is running xp home and the second is running xp pro, router is Netgear WGR614 v2)

Are the two computers on the same subnet? Are you wanting to play games between these two computers? Or are you wanting to open a port for internet users?

Yes they are, the problem is that the router is on the same subnet of only one of the computers, and i want to forward a port to the other one, for a p2p application.

That does not make sense. If the two computers are on the same subnet and the router is on the same subnet as one of the computers, then unless you have a computer setup with dual nics on two different subnets, then the all three machines should be on the same subnet.
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If this is the case, why not have the `middle` computer, the one on two subnets act as a gateway for the isolated computer. Set that computers gateway to the `middle` computer's ip address.

Thats how i have it set up, but it doesnt solve the problem because the router forwards the incoming port to the ip of that middle computer, and i want it to forward to the isolated computer. The router does not have direct access to it since it isnt on the same subnet, so i dont know how to do it.
That is my question

Is there any function of xp that can do this or a software or something?

Ok. Now I see your setup. Here is a tricky but effective solution. You can use something like putty or secure shell to forward the middle machines port n to the isolated machines port n. What this is actually doing is passing this information from one machine to another machine. I am not quite sure if you wan to get this involved but the command from putty would be something similar to this
-R 1521:127.0.0.1:1521 middle_machine_ip
This is run from the isolated machine and would force all activity on port 1521 of that machine to be forwarded to 1521 on the local machine.
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Like I said this is somewhat involved and not the most straight forward approach but this is what comes to mind right away.

Alright thanks man !

Ill try it and see if it works.