We have a customer that wants us to connect to their site using
XP's built in VPN client. We are behind a BorderManager 3.7 firewall.

What ports need to be opened on our BorderManager firewall to allow us
connect to their VPN?

Also, is there any issue with Dynamic NAT that BorderManager uses for

outgoing connections and the Windows XP VPN?

I looked in Craig's book but could not find an example for the ports needed for the Windows XP VPN.