ZoneAlarm (FREE)

This firewall by ZoneLabs Inc., has got one of the best and the most preferred firewalls around on the Internet. You can select the level of security and alert frequency. Has got a anti-spam feature in it too (I dont use it though)

I like it coz' :

• Makes me feel secure on the Internet (though security is ALWAYS a doubt)
• Doesn't bother me too much
• Hides my IP from the outside world
• Anti-Spyware feature
• FREE !
  

I hate it coz' :

• SOMETIMES a memory hog (vsmon.exe usually)
• Slow startup time
• "Are you really sure you want to quit ? Yes/No" feature
• Anti-spyware scan takes FOREVER to complete

Link :
www.zonelabs.com