Stand-alone product similar to Safe Web

I am still using NS version 21.7.0.11 because I need the Network Security Map. 

However, Norton Safe Web does not work with Firefox on this version.

Does anyone know of a standalone product that will check search results in Firefox?  I have tried WOT, but it's results are largely based on people's opinions about a website's content.  I am only interested in knowing about computer threats, malware/adware/viruses etc.

Any ideas?