yo te recomendaría mas que un antivirus una Suite de seguridad, en mi caso utilizo en win2 Comodo Internet Security la cual incluye todo esto gratuitamente
Internet Security Includes:
Antivirus: Tracks down and destroy any existing malware hiding in a PC.
Anti-Spyware: Detects spyware threats and destroys each infection.
Anti-Rootkit: Scans, detects & removes rootkits on your computer.
Bot Protection: Prevents malicious software turning your PC into a zombie.
Defense+: Protects critical system files and blocks malware before it installs.
Auto Sandbox Technology™: Runs unknown files in an isolated environment where they can cause no damage.
Memory Firewall: Cutting-edge protection against sophisticated buffer overflow attacks.
Anti-Malware Kills malicious processes before they can do harm.
mas info:
http://www.comodo.com/home/internet-security/free-internet-security.php
salu2 xD