From LedHed's Wiki
How to disable the XP firewall from the commandline
There are many Network Administration tasks that can't be accomplished when the XP Firewall is enabled. Since the release of XP SP2 the Firewall is enabled by default. Here is a way to disable the firewall from the commandline which can be very usefull.
Contents
Prerequisites
You must have access to the PC you want to disable the Firewall on.
Possible options: Local access, a remote shell like telnet, or you must have admin access to the computer and be on another computer within the same subnet.
Checking the Firewall Status
The 'SC' command allows us to check the firewall status.
sc firewall show opmode
Disabling the Firewall
sc firewall set opmode DISABLE
Enabling the Firewall
sc firewall set opmode ENABLE
Notes
1) You can also disable the XP Firewall via Group Policy is your computers are on a Windows 2000+ domain.