Anybody that thinks SP2's Windows Firewall is such a large improvement had better make sure that they know all the facts. If you believe you need a firewall you will still not want to rely upon SP2's built in Firewall. All of the hype behind Service Pack 2's Firewall may lead most people to believe that Windows Firewall is all they need to stay safe. All of the marketing buzz gives people a false sense of security. While this IS a large step in the right direction it still is nowhere near where it should be. Anybody currently using or planning on using SP2 had better read through this carefully to find out WHY it's not anywhere near as secure as the marketing team will try to make you think.

From this document:

Windows XP Service Pack 2 (SP2), currently in Beta testing, includes the Windows Firewall, a significant enhancement of the feature previously known as the Internet Connection Firewall (ICF). Windows Firewall is a stateful host firewall that drops all unsolicited incoming traffic that does not correspond to either traffic sent in response to a request of the computer (solicited traffic) or unsolicited traffic that has been specified as allowed (excepted traffic). This behavior of Windows Firewall provides a level of protection from malicious users and programs that use unsolicited incoming traffic to attack computers. With the exception of some Internet Control Message Protocol (ICMP) messages, Windows Firewall does not drop outgoing traffic.

Humor: MS's Spell checker suggested the word shameful for stateful which would make it: Windows Firewall is a shameful host firewall :)