Is the Windows XP firewall good enough?

"For inbound protection the answer would be : Yes, it is sufficient.

For outbound protection, the answer would be : No, insufficient.

Even the improved Windows Vista version of the firewall still scores poorly when it comes to outbound protection.

See the articles below for an in-depth analysis of the strengths and weaknesses of the Windows Firewall (applies to both XP and Vista):

Analysis: New Windows Vista Firewall Fails on Outbound Security

Windows Firewall Review (XP)

If you computer is virus and malware free to begin with, and you are vigilant about keeping a modern antivirus/malware suite constantly updated, then running the Windows Firewall alone should be sufficient."

"The windows firewall will block all attemts to connect to your computer from the outside - those are the ones that might break into your previously unbreached system. If you're behind a NAT router (usually the case when you use WiFi), even that is not necessary, since the router has the same effect.

The only additional benefit a third-party firewall can offer is to alert/protect you when your computer is already infected with something that tries to ""phone home"" - but chances are that a real virus will disable the firewall anyway; and nowadays there's so much stuff that connects to the net in some form (often looking for updates) that any malicious activity probably gets drowned in the noise."