Configuring router for VPN

I am trying to configure a router to accept VPN connections. These are the steps i have taken so far.
I have forwarded all necessary ports required for VPN.
The router is a netgear wnr2000.
I am trying to connect from outside the network. The IP i am trying to connect to is the WAN IP address… Is this correct ?
I am using Windows XP Pro on the server and connecting from home with a vista laptop. When trying to connect I receive the error, there is not a vpn server actively listening for connections.

Is there any thing else I should have to do with the router?
Should I assign a static IP address for the computer that is listening for VPN connections ?
I am a little new to this, as you can tell, all help is appreciated. Thank you.