Post your links to free antivirus and firware software here. Reviews and opinions of the software would also be useful for people.
Free Antivirus Software
AntiVir Review
Avast!
AVG
BitDefender
Review: Antivirus Software Roundup
Performance testing of antivirus software
Free Firewall Software
Kerio Personal Firewall
Omniquad
Outpost
Sygate Personal Firewall
ZoneAlarm
Free Spam Killer Software
Email Remover
SpamButcher
Free Spyware Removal Software
Ad-Aware SE Personal Edition
PAL Spyware Remover