Best Free Firewall?

I'm using Adaware, Spybot, SpywareBlaster, AVG 7.0 and A Squared on a Win XP machine with no SP1 or SP2 updates.
Am I missing any programs that the fine experts on this BB can recommend?
Thanks.

 

How about Service Pack 2 ?

 

Thanks again PeteC. I downloaded and installed zonealarm.
Your recommendation is always tops with me.
Vic

 

skaler2k--I also use Zone Alarm (free).
And as you know from our other conversation, why do you not update to WinXP SP2? As mentioned in that conversation, you no longer are able to download Security updates from Windows Updates. Many of these are important to the security of your PC. Adamt56 raises the same question.
The only thing to be aware of then, is that SP2 installs Windows Firewall by default. Since you have Zone Alarm, you will want to disable Windows Firewall since you should have only one firewall running. (Control Panel|Windows Firewall)