I need to create a rule on one of those m$ ISA things that will allow
traffic arriving on the ISA's external NIC IP address, port xyz be
forwarded to internal server IP address, port 80.

I have, among others, the option to create a web site publishing rule,
a non-web-site publishing rule or an access rule. Any hints? Am I going
in the wrong direction (other than the fact that I am using (m$).