As new threats emerge, Symantec immediately builds new protection updates and makes them available for download on a subscription basis.
Norton AntiVirus automatically detects and removes viruses and also offers automatic protection against the latest threats with set-and-forget convenience
The virus definitions installer you should download depends on the type of processor your Mac has (PowerPC or Intel), the Mac OS version, and the version of Norton AntiVirus or Symantec AntiVirus you are running.
Requirements:
· 128 MB of RAM.
· 100 MB of available hard disk space.
· Internet connection required for LiveUpdate.
· Norton Antivirus 11.x
Intel only 
