Is Opening Firewall Ports Risky?
Every port you open makes your computer more vulnerable. However, opening a few ports in order to play a game or run a video conferencing application, for example, still leaves your system protected against the most common intruders. When you add a program to Windows Firewall, it only opens the necessary ports when that program is actually running; once you exit the program, the ports are then closed.
Hope this has put your mind at rest?