Ad-Aware Free
A-squared Free 4.0
Ashampoo FireWall Free
AVG Anti-Virus Free Edition
Avira AntiVir Personal Avira Anti-rootkit Tool
BitDefender Free Edition BitDefender Free Conficker Removal Tool BitDefender Quickscan (online scanner)
ClamWin Free Antivirus
Comodo BOClean
Comodo Instant Malware Analysis (online scanner)
Free Comodo Internet Security (firewall+antivirus+hips)
Comodo AntiSpam
Free Dr. Web CureIt Utility
DriveSentry next generation antivirus (antivirus+HIPS)
GeSWall (Host intrusion prevention system)
GhostWall (firewall)
Kaspersky Online File Scanner 
Sunbelt Personal Firewall
LinkScanner Online
MailWasher Free (antispam)
Malwarebytes Anti-Malware
McAfee SiteAdvisor
Online Armor Free (firewall)
Outpost Firewall 2009 Free Edition
Panda Anti-Rootkit
Panda ActiveScan 2.0 (Online antivirus scanner) Panda USB Vaccine
PC Tools AntiVirus Free Edition
PC Tools Firewall Plus
Spyware Doctor Enterprise Free Edition 
Returnil Virtual System 2008 Personal
Rising Antivirus Free Edition (antivirus+HIPS)
Prevx CSI 3.0 (*free version only scans computer)
SafeSpace Personal Edition (virtualization)
Sandboxie (virtualization/sandbox)
Sophos Anti-Rootkit
Sophos Conficker Removal Tool
Spybot Search&Destroy (antispyware+HIPS)
Spyware Terminator (antispyware+HIPS)
W32.Downadup Removal Tool (Symantec)
SUPERAntiSpyware Free Version
System Protect (file protection software)
Secunia Personal Software Inspector 
SpywareBlaster 4.1 
ThreatFire (antivirus+HIPS)
Virus Total Online Scanner
Web Security Guard
Windows Defender (Vista and Windows 7 users have it already)
WinPatrol 2009
Web Of Trust
ZoneAlarm Free Firewall
