Here is one of the best virus scanner personally i found this the best and Anti-virus around , McAfee VirusScan Enterprise with Patch 1 released by DVT !
This release of VirusScan Enterprise 8.7i contains defect fixes, incorporates the Beta 2 release of the 5300 scanning engine, and a number of features that improve performance of malware scanning and incorporates functional and usability improvements. Providing this new functionality required making architectural changes to the product infrastructure. While we have performed extensive testing to ensure that these changes don’t impact the overall stability of the product, we urge you to download this beta version, test all features in environments that are similar to your production environments, and provide us feedback to help us further improve the stability and quality of the release.

Features:
Comprehensive McAfee anti-virus protection
Potentially unwanted program security
Buffer overflow prevention (IPS feature)
Complete outbreak response
Port blocking/lockdown (firewall feature)
Application monitoring: email engines (firewall feature)
File blocking, directory lockdown, folder/share blocking (IPS feature)
Infection trace and block
Powerful memory scanning
Centralized management and reporting
Enhanced email scanning
Protection from threats that use scripts
Optimized for mobile users

http://rapidshare.com/files/238525021/McAfe.VirusScan_RapidRise.org.rar