Friend has relatively new custom built PC -AMD 3000, 512 MB ram,Win Xp with SP2 installed, Norton antivirus and personal firewall. Cable broadband connection via a router and ethernet port. After SP2 installed ran shields up on grc.com which showed Port 80 open.I don't know situation prior to SP2 install (mate knows very little about PC's and has never checked firewall)but wonder if this is connected in some way to router. i.e. does port 80 have to stay open to communicate with router and will all be closed on internet side of router. Any info would be of great value including how to close said port 80 if needed. Thanks.
TomJerry if you have no firewall between your computer and the router then internally all the ports will be open. The router MUST have port 80 open otherwise you would not be able to access any internet site.