You will get Virex with your .Mac subscription. I have that and I have never used it. I have heard that Norton may mess up your system more than it helps.
IMO, you don't need any anti-virus software right now. There is no virus around currently. If you keep visiting these forums, you would definitely know when one comes up. Then probably you can install virex.
Liek they said, you already have the best anti-virus software: OS X. There are no major viruses for OS X. Sure Norton and a few other companies make anti-virus software for Mac, but they really are not necessary.
People here will tell you horror stories of running anti-virus software on their systems. You are very well protected
While it is true that OS X is virtually virus free, and likely to be so, I would consider it unwise not to have virus scanning software. Unless you never have to interact with Windows users, there is always a possibility that one may unintentionally infect Windows users.
I used both Symantec and McAfee (.Mac), but based on Macworld's recent review of Intego's VirusBarrier, I would have to say that it is the best Mac virus scanning software out there. Symantec is in need of an update, and Virex (I thought) was a bit slow.
Fair enough, but some people (me for example) HAVE to use Windows which means that all my Macs run antivirus just in case (Norton for the record). It's unfortunate, but it's the way it is. The day someone ports some good CAD programs to OSX...
I like the idea that people with surplus help out a little extra when amongst those who hasn't; and I use virex, evertime my boyfriend has used my mac to check out suspecious mails. Occasionally it finds something nasty and gets rid of it before I pass it on to unfortunate windows users.