Configuring router for VPN passthrough

As my title says I need some help with configuring router for vpn passthrough. Here is a small glimpse of my network. I am on FiOS internet setup. The router which I am using is some WI152WR. The connection was configured by Verizon guy. Now I have a Windows Server which is the centeral DC in the entier newtork. There are other 4 systems configured on the same network. Here I want some settings through which the router can pass request via XP system so that those who are on laptops or other system can able to access it. I want them to connect as VPN client. Everything works inside a firewall here.

You can try checking the documentation of router. It would give you a glimpse of setup. If you want you can try go with the internal setup. You can try to setup a Windows Network Connection Windows XP and create a common workplace for all. The settings are as follows. Go on Network Connection and then click on Make a new connection. Now click on setup an advance connection and click click on accept incoming connection. There you will find one more settings, allow virtual private connections. That's all.

I too have the same issue. I am facing issue here with port forwarding. This is not working properly through my vpn. I do not know about the settings, but I think it is using pptp.