I have Windows XP now but ran Win98 for a long time, even after Microsoft stopped their security updates for that OS. I was just fine with Avast and had no firewall for a couple of years.
Now that I have XP, I use Avast again but still have no firewall (unless there is one in this OS that I wasn’t aware of). Do you think I need one? If so, is there a good freeware firewall that works well with Avast?
Most all firewalls work well with Avast!, but take a look at http://forum.avast.com/index.php?topic=42538.0 and search for other firewall threads for some specifics. In the meantime, go to the XP Security Center (via Control Panel) and turn on the Windows Firewall. It is inbound only, but does its job pretty well if you are careful. And, of course, runs fine with Avast!
I use and recommend comodo which is free, you can check it out at http://www.personalfirewall.comodo.com/
Hi all…
With Service Pack 2 and 3, Windows Firewall is enabled by default so the OP probably doesn’t have to do anything. It is switched off when a third party firewall is installed. 
May God Bless you all!