All I can say is, wow.
When I originally downloaded and installed ClamXav, I used it entirely from the command-line. Which is funny, because it's whole reason for being was to lend a GUI hand to the command-line, open source clamav engine. But ClamXav has made immense strides in the short year since its first appearance, and in it's latest incarnation, the GUI has features that totally and completely rock. Namely: Sentry.
Okay, let me back up and explain just what ClamXav is. ClamXav is virus detection software for your Mac, and it's free. That's right, free. Though the author will take donations, which I highly suggest we all go give him, so that he keeps providing this wonderful software. For free. ClamXav is basically a GUI wrapper for the open source clamav virus detection software for other UNIX systems, which has been around for some time now. ClamXav installs that engine, and provides a lovely (well, it's not the most beautiful software, but it's quite functional and easy to understand) GUI frontend that allows you to schdule virus scans, and create watch folders, among other things. One nice thing about ClamXav is that it uses standard UNIX goodness to accomplish its goals. So, for instance, when you set up the scheduler, it's just editing your user crontab. Nice. I might suggest to the author, for multi-user environments, a way to schedule scans via the global crontab as well. For now, if you want to do that, you'll have to edit /etc/crontab yourself.
I must stress here that, despite its free-ness, ClamXav, in my experience, is also the most accurate of the virus scanners. I've tried Norton, Virex, and Sophos, and they all failed to catch viruses that ClamXav was able to find. ClamXav even flagged that mp3 trojan that was floating around awhile ago. Pretty cool that it can catch viruses on a platform that hardly has any, where other software fails. In fact, it's so good, Apple now includes the clamav engine as part of the mail server In Tiger Server. If that's not a ringing endorsement, I don't know what is.
One of my major beefs with ClamXav in the past was the lack of folder watching, which to me seems pretty necessary. But the latest version has what's called a "Sentry" feature, which watches any folder you tell it to, and scans it for viruses whenever something is added to the folder. Nice. Using this to scan your mail can be tricky to set up, but it's do-able for IMAP mail in Panther (but not POP mail), and in Tiger, should be possible for all your mail (including POP, which Tiger now breaks up into individual files, instead of using one big mbox file). So that's great.
The one thing ClamXav lacks -- and will probably always lack -- that Norton AntiVirus has, is the ability to repair viruses. If you've ever had a Word file with a virus -- and God knows I have -- you know they're intractable. And what do you do if you really need that file? ClamXav cannot repair the file for you. Norton can. And that's importatnt.
My method is to use ClamXav for scanning, and NAV for repairs. I never install Norton as it always seems to break something, and is impossible to uninstall. But I keep it handy, just in case I actually do get a virus I need to cure. Hopefully, with ClamXav's new sentry feature, I'll be getting fewer and fewer viruses anyway, so it shouldn't be a big deal. You know, an ounce of prevention, and all that, right?
If you haven't tried ClamXav, I highly recommend you do so. Now. And don't give me any of that "There are no viruses for the Mac" crap. If that's your attitude towards virus protection, then please don't read this article.