Windows 7 Beta is not immune to computer virus . So here some list of anti-virus that currently can be used for Windows 7.
Norton 360 3.0 beta works on Windows 7 Beta.
Kaspersky Internet Security 2009.
AVG Internet Security and AVG Anti-Virus works with Windows 7.
NOD32 works in Windows 7 Beta.
Avast Home (Free) and ESET Smart Security works well.
Bitdefender works well.
McAfee VirusScan Enterprise + AntiSpyware Enterprise 8.7.0i is working without any problems.
Avira AntiVir Personal and Avira Premium Security Suite Version 9 works fine.
Subelt VIPER working.