Disabling Windows XP Firewall
Windows XP contains a simple firewall, and Windows XP Service Pack 2 upgrades the firewall with more sophisticated functionality, including the ability to block specific applications from communicating over the internet. This provides much greater control but may hinder programs which legitimately require internet connectivity, such as anti-virus programs, email and remote access.
It is possible to configure the firewall to allow programs to communicate properly, but if your system is behind a firewall closer to the internet, such as a corporate LAN firewall or an ADSL router, the Windows firewall can be simply disabled without creating any security risk.
To do this:
If you are using a dial-up connection to the internet, or another type of direct connection, the firewall should remain on.