There is a small freeware Utility called CurrPorts from Nirsoft that displays all open ports on windows.
Download CurrPorts to your computer:
32Bit version: http://www.nirsoft.net/utils/cports.zip
64Bit version: http://www.nirsoft.net/utils/cports-x64.zip
Unpack the .zip file and double click on the file cports.exe to start CurrPorts. The application will show you a list of all open ports and offers the ability to apply filters on the list.