Online Armor Firewall - Simply the best free firewall available! Was the first to pass 100% of leak tests out of the box and continues to shine. Offers great protection through a host of security features (including HIPS) yet remains very easy to use. It’s this rare combination of performance and simplicity which makes Online Armor a top contender. (XP/Vista 32bit)
Comodo Firewall - Offers excellent protection but is somewhat complicated for the not so savvy and engenders a fair amount of user complaints, e.g. uninstall process very difficult, far too many popups, bad at remembering previous decisions/input. It seems the ‘experts’ like this one but ‘users’ generally do not. Maybe that can be put down to inexperience. One for the expert user perhaps. Comodo includes AntiVirus - We recommend you disable Comodo's antivirus during installation/setup and choose an AntiVirus program from our Free AntiVirus List. (XP/Vista 32/64bit)
PC Tools Firewall - Simplicity makes this a good choice for novice users but again, complaints of excessive popups and system slow downs take the shine off somewhat. (XP/Vista 32bit)