While surfin' around, I found this little helpful tool on microsoft.com. If you want to examine the usage of your ports by software and you are totally overstrained by using netmon - this is your tool! You just have to get familiar with the eventlog ;-)

"Port Reporter logs TCP and UDP port activity on a local Windows system. Port Reporter is a small application that runs as a service on Windows 2000, Windows XP, and Windows Server 2003." Download Port Reporter a logging service for Windows that logs TCP/IP port usage data.