The Windows Team Blog have a new post about AV software that works on Windows 7 Beta - it's worth a read if you don't already have one installed 
You can read the full blog post here.Folks have been asking about anti-virus solutions that work with the Windows 7 Beta. In anticipation of this, Microsoft has been actively working with security partners to help them get their applications ready for Windows 7. Three security vendors have taken the build we released to developers at the PDC in October and have developed solutions available today that work with the Windows 7 Beta. The following anti-virus solutions are available via Windows 7 Security Provider page:
It is great to see that these partners were able to have their solutions working so early in our development process. We will add additional partners to the Windows 7 Security Provider page when they make Windows 7 versions publicly available.
- Symantec offers the Norton 360 3.0 Beta which works on the Windows 7 Beta
- AVG offers AVG Internet Security and AVG Anti-Virus that works with the Windows 7 Beta
- Kaspersky is offering a technical preview of Kaspersky Anti-Virus for Windows 7.