technicly if you got the windows xp builtin firewall enabled then you do have a firewall a real lousy one but still , goto start-->settings-->network connections-->right click "local area network" if your directly connected to the internet (without a dialer) or right click the dialer if you arent and goto "advanced" tab and click "settings" (will be greyd out if you have the xp firewall disabled) tick "web server" click ok and again and thats it , if your not using any good firewall then youll better have at least the xp one enabled its unsafe to be with no firewall at all , but keep in mind the xp firewall is as said before "lousy" it can block only certain incoming ports and it have no application control whatsoever