There a ZERO viruses for Macs which means NO issues. Now go and check Norton's Mac support page and count the issues (thousands). Bottom line: Installing anti-virus software on a Mac will subject you to problems you will never otherwise suffer. A Windows user is a fool if they don't run AV software and a Mac user is a fool if they do.

Symantec came out with a new version with Tiger. New OS, pay again for Virus Protection. But that may be their downfall. When I upgraded to Tiger, I ditched Norton because I had become a savvy Mac user and realized "no threats". I also discontinued using their useless firewall at the same time. My system is Norton Free!

I disagree that a Mac user is a fool for not running anti-virus software. I have had viruses on my Mac - simple-to-detect MS Word viruses - which, were I to send them on to Windows-using friends, would be putting their machines further at risk.

Sure, there's no way they could affect my computer(s), and I practise safe hex, and I could easily get away without running anti-virus software (ClamXAV, since you asked). But I keep it on there. Just in case.

I agree that paying money to Symantec for their protection is not necessarily a good idea.

Seriously, if you think that there are "no threats" for Leopard you need to wake up. You aren't hurting PC users with snide remarks, they don't care that you use Mac OS X, however they probably will laugh at you once you do suffer a problem for not taking proper precautions. All you have to do to realize that there are security flaws in Mac OS X in general and Leopard in particular is read the front page of MacObserver right now. Look for "DoS". Just one of the many threats that exist, and one of the very few that are publicly known. As has been stated countless times by security professionals one of the weakpoints unique to Mac OS X is the Mach kernel and its integration with BSD. The flawed integration allows you to circumvent many of the security features of BSD, making Mac OS X weaker than BSD in general. But don't fool yourself into thinking this is the only known vulnerability in OS X. There was also a VPN DoS threat discovered about a week ago. Mac OS X is still below the market share threshold that makes a piece of software a lucrative target, it needs to about double in market share before it hits that mark which is somewhere between 10 & 15%. So everything you are seeing now is mainly just the results of some security minded people who are interested in the Mac platform. When people with malicious intent start seeing profit potential in designing attacks for the platform, well, that's when we are in for some trouble, and that's when you'll be upset you weren't following secure practices. Security is not a Windows problem, it's just a problem. Not advocating any specific software suite, that's a personal preference, but you better wise up and not make yourself a victim.