For those beginners who don't have a clue what a firewall is, or have no clue how to install one, the Service Pack 2 firewall is great. It is in-built, quite powerful, is turned on by default, and it's the easiest option available. But one main difference that SP2's firewall doesn't do which other software firewalls (like ZA) do is: block and filter outbound connections. This allows spyware to collect information once it's on the computer and send it back to the author. This is invasion of privacy, which Zone Alarm (among others) would stop!

I'm in no way saying Zone Alarm is inpenetrable: it has faults of it's own. Also, over time, SP2's firewall will be unlikely to have many conflicts because of tech support/updates.

Please add any other major differences in the SP2 firewall and ZA/software ones and give your views.