Utility for viewing open ports and which program is using them?

Question

For security reasons, I would like to be able to see exactly which ports are open and the name of the program listening on them. I'm using Windows XP.

Answer 1

GRC Shields up, http://www.grc.com/intro.htm and Sygate Online Services, http://scan.sygate.com/

They will identify open ports on your system but will not tell you which programs are using it. However, if you are behind a router, hardware or software firewall, it will most likely find all your ports are stealthed (or closed).