Comments:
The issue of firewalls and Avast has come up many times, and there is really no one way to go. As has been said here in the previous posts, all combinations have been tried on various operating systems.
I guess my contribution here will be to name each of the "free" front runners and my experiences with them.
FirewallsZone Alarm
Sygate
Agnitum Outpost
Kerio
Tiny
Firewalls can be application based or rule based.
Application based fws are very user friendly and "learn" pretty much by themselves. Rule based allow "customization" of how programs access the internet, and the user can restrict them or extend their access as wishes dictate. They do require a bit more knowledge and configuration.
ZA is application based. Very easy to use. Works fine in all OS, and with Avast.
Sygate is App/Rule. It can be used "out of the box" without any special configuration or customized. I have set special rules since I use IE and have increased security when IE accesses the net.
Sygate can be unstable at times in my Win98 but works fine with ME and XP. Sygate loves Avast.
Kerio is also App/Rule based. I used it twice but removed it. I did not like the constant "popup permission windows". Although it got along fine with Avast, it did not get along with me.
Outpost was fine. Stable, user friendly and was ok with Avast.
Tiny Personal firewall has a difficult learning curve and I do not recommend it, although it does a very good job of securing a computer.
I stick with ZA and Sygate on my Win98/ME/XP systems.
Good luck
Techie
Techie