- Norton AntiVirus 2006
- Norton Internet Security 2006
- Norton Internet Security - Anti Spyware Edition 2005 or
- Norton System Works 2006
Otherwise, if you just visit certain websites which have crafted their webpages to exploit recently-discovered critical vulnerabilities in that software, an attacker could infect your computer with malware and even take control of your computer.
It's ironic that products designed to enhance computer security and internet security could themselves create a security risk enabling bad guys to stuff your computer with viruses etc.
According to Symantec no one had been infected yet at the time they announced the issue, and other Symantec products seem to be OK, but better to be safe than sorry.
(Via my fave security news site Heise Security, which also suggested that this only affected Windows PCs but I've not seen that confirmation elsewhere so personally I'd update even with a Mac or Linux.)