Computer viruses are, unfortunately, a fact of life these days. And although we Mac users don't experience the onslaught of malware that folks in the Windows camp have to fight off, we're not invulnerable, and we mustn't become complacent. An antivirus program is a must.

Symantec's Norton AntiVirus for Macintosh 8.0.2 is the first OS X­native release of this well-regarded protection tool, and in addition to OS X 10.1 support, this version offers improved scanning capabilities.

Norton AntiVirus provides multiple ways to track down viruses. It includes a scanner application and an invisible background process called AutoProtect, which looks out for viruses, alerts you when it finds them, and stops them before they can propagate further.

AutoProtect is the first line of defense, but because it operates in the background and relies on a kernel extension (which is akin to a system extension in OS 9 and earlier systems), some users may prefer not to use it. If you fall into this group, you can also root out viruses with either the scanner application or the included navx command-line tool--useful for building Unix shell scripts, for example.

Version 8.0's most useful scanning feature is QuickScan, which remembers previously scanned files and will rescan them only if you've made changes to the file or if you've updated the virus definitions. Rescanning an already-scanned disk now takes only a fraction of the time a first scan does. And unlike its predecessors, Norton AntiVirus 8.0's QuickScan also remembers already-scanned archives.

After installing AntiVirus 8.0, you should first ensure that the program's virus definitions are up-to-date. To this end, the program includes an OS X version of LiveUpdate, an application that queries Symantec and downloads new virus definitions--and software updates--as needed.

AntiVirus 8.0 also includes Scheduler, which lets you schedule regular antivirus scans to make sure no viruses have somehow sneaked onto your system. The software can alert you when your virus definitions are more than a month old and then download updated ones for you.

One area where AntiVirus falls short is in the comprehensiveness of its virus definitions: it detects only viruses that can infect Macs, including macro viruses that affect Microsoft Office apps. Even though Macs are immune to PC viruses, they are sometimes unwitting carriers. Since Macs and PCs often coexist closely, it would be useful if the package detected PC viruses, especially those that are transmitted via e-mail. Likewise, this lack of detection is especially problematic for Mac-based users of Connectix's Virtual PC, who, for performance reasons, might not want to run a PC-based antivirus app.

In addition, version 8.0 has disappointingly OS 9­centric documentation. While the installation CD includes Norton AntiVirus 7.0 for OS 8 and 9, we found OS X content treated as the exception rather than the rule. This was particularly apparent in the online help.

Macworld's Buying Advice

With the exception of PC virus detection, Norton AntiVirus for Macintosh 8.0.2 provides the tools necessary to keep your Mac free of viruses. The responsibility for updating your virus definitions, however, remains with you.