I probably didn't make it very clear but when I said I had three network connections I meant the connection Icons in Network properties, not three network adapters. You description of the physical setup is correct - an external ADSL modem and two network adapters on the server. I have the private network using DHCP (I think this is a requirement of the ICS anyway) and I do not have an IP address assigned to the Internet connection - it is also dynamically allocated by the bigpond server.
I have not removed the dial up connection's drivers or TCP/IP settings as I was waiting to make sure the ADSL connection all worked properly first. Might this be the cause of the erratic behaviour for the clients connection?
