This is what i found on official Windows 7 site. They illustrated specially made antivirus exclusively for windows 7 from the top 3 antivirus companies - Kaspersky , Norton and AVG.
All of these releasing the beta trial version for testing on windows 7.
The companies listed below provide security software that is compatible with Windows 7. Just click the company name to see the Windows 7-compatible product they offer.
Microsoft is actively working with the partners listed on this page and additional security independent software vendors (ISVs) to provide security software solutions tested on the Windows 7 Beta.