Here's a handy command you can use on windows to list all of the open TCP/IP ports:
netstat -anop TCP
Need to list open UDP ports? You guessed it, try this:
netstat -anop UDP
Quite handy when you want to see if a program did indeed bind to a port. It is essentially an easy way to port scan yourself on windows.
This command is built in to windows, but there are some third party tools such as Foundstone's fport.exe which also shows which program binds to the port.