The University of Toronto’s subscription to Symantec Endpoint Protection has expired and will not be renewed (so the software engine will stop being upgraded, eventually leaving machines vulnerable). Please see http://antivirus.utoronto.ca/ for more information from the people at the Licensed Software Office (there are links for Antivirus for Students and Antivirus for Faculty & Staff).
On personally owned computers running Windows it is simplest to download Microsoft Security Essentials from Microsoft, uninstall the Symantec software, and then install the Security Essentials.
On other computers there is a some free software that they recommend, or you can purchase Microsoft System Center Endpoint Protection 2012 which can be purchased through UShop. The cost is $3.25 per user/device per 12 month period. It has been placed under the following category:
Software > Microsoft > Microsoft Servers > System Center Endpoint Protection (Forefront)
It also should be installed after removing the Symantec software.
For Apple OSX computers they recommend downloading the free ClamXav anti-virus software.