Personally, I dont rely on the iana port listings to determine what is responsible for opening ports on a host. I prefer finding out what application is opening these ports.

For example, if you see port 1433 open on your machine, never assume that mssql is responsible for opening it. What if someone has installed netcat on your machine or a trojan, and configured it to open port 1433?

I use a tool called Active Ports on my WinDoze machine. Its pretty good, it will tell you what application is responsible for each open port. Similiar to the netstat -pa command on linux, but with a pretty interface