Here is a pretty good list of Antivirus and Malware Detection/Removal Tools.

• Ad-Aware– Anti-malware
• A-Squared Free– Anti-malware
• Anti-Malware Toolkit– A program that automatically downloads all of the recommended programs to help users clean their computers.
• Avast – Free Antivirus home editions for Windows or Linux. I use the Windows version.
• AVG Software– A Great free AV / Anti-Malware solution.
• Bitdefender 60 second Antivirus – Very fast virus check.
• Blink– Comprehensive Antivirus and Anti-malware.
• BotHunter – Checks your network for Botnet Activity.
• ComboFix– Removes hard to remove malware.
• Comodo– The awesome firewall company now makes a complete free internet security suite.
• Counter Spy – Sunbelt Software offer’s a free trial of this popular software.
• Cyberdefender– All in one Anti-virus and Anti-malware.
• D7 – Awesome all-in-one Malware removal & Windows Repair tool.
• DrWeb CureIt– Free DrWeb Antivirus/Antimalware program.
• FreeFixer – malware cleaner
• GMER – Rootkit Detector and Remover.
• HitmanPro – All Around Malware Remover.
• IOBit Security 360 – Free Malware Removal includes real-time protection.
• OTL –  Oldtimer’s Listit malware removal tool ———————–***Portable***
• Malware Bytes– Another Malware Removal Tool.
• Microsoft Security Essentials – AV and Anti-malware freebie from Microsoft
• Pandasecurity’s Anti-Rootkit– Free Anti-Rootkit software.
• Rkill – kills processes, malware included.
• Roguefix– Rogue scanner and Fake Warning removal tool.
• RogueKiller – Malware detector and remover.
• SecureIT Internet Security Suite – A full Free Security Suite
• SmitFraudFix– Malware detector/remover.
• Spybot Search and Destroy– Anti-malware that scans for infection.
• Spyware Doctor– A link to Google Pack, I recommend grabbing the free Spyware Doctor.
• Spyware Blaster– Anti-malware program that prevents infection.
• Super-Antispyware– Super anti-malware remover. Portable version available.
• Threatfire– Anti-Malware/Antivirus.
• UVK – Ultra Virus Killer, Works great at what the name says.
• Vundofix– VundoFix is a freeware removal tool for many of the known variants of Trojan.Vundo, Trojan.Conhook and other similar infections.
• WinPatrol– Monitors your registry and startups and more to prevent infection.
• WinPatrolToGo – Analyze what’s installed and running on any computer! – – – ***Portable***
• WinPooch– Open Source Anti Spyware and Anti Trojan that also makes ClamWin A-V a realtime scanner.