online games on my ps3? ive heard that can be unsafe, would it still be unsafe if ive got the latest version of Norton Antivirus with the latest definitions?

or is it as safe as it is when 'upnp' is disabled?
i run my pc and ps3 through the same router, im assuming there would be no security issues on my ps3 with upnp enabled, and that there would be some on my pc.