After fixing the bugs from beta versions now the final Avast Antivirus 5.1 is out there for general public and available free for download to protect your systems against viruses, trojans and other harmful threats.
Avast Antivirus 5.1 Improvements:
Improved 64-bit support which include 64-bit boot-time scanner and 64-bit Outlook Antispam Toolbar for Outlook 2010
Improved cleaning of malware infections
Improvements in Behavior Shield and better handling of false positives.
Improvements in antirootkit engine and cleaning module.
Enhanced stability and performance improvements in Web Shield and [...]