1. Configure your PC's inside the network with Static IP addresses. (or configure your DHCP server with address reservations for those machines)
2. Configure your NAT router to port forward specific external ports to specific internal machines
winxp 192.168.1.2 - forward port for vnc
redhat linux9 192.168.1.3 - Forward port 22 for ssh
3. Use a service such as no-ip or dynip to assign a Domain name to your Dynamic connection.
4. Configure your router or an dynamic IP agent on your workstation to update the Dynamic DNS entry automatically.
5. connect to your machines remotely using your new domain name !!