Two Firewalls Can Work At Once

By all means, turn one off. Using more than one firewall does not make your system any safer. It just makes it harder to manage inbound and outbound traffic by setting rules, policies, and exceptions because you now have twice as much work. Most experts suggest you use a third-party product over WinXP’s built-in firewall because the Windows version only protects against malicious inbound traffic. If you’ve unknowingly installed a piece of spyware that begins to send your personal data over the Internet, Windows Firewall has no way of protecting against it. (The firewall in Windows Vista does protect against malicious outbound traffic, but users have to configure the protection themselves because it’s turned off by default.)