Computer viruses -- or is it "virii"? -- make good headlines. They're scary and mysterious, they resonate with our fear of biological viruses. They're just about the only exciting facet of computing to many readers.

I used to think this fear was overblown. I still think it is. But not for people who use networks.

Headlines make viruses sound like the biggest threat to your computing. They aren't. Not backing up your data, not learning the ins and outs of your application programs, not putting enough memory in your computer, not organizing your hard disk, not upgrading to the latest version of your applications: These directly hurt your computing efforts every day. You just aren't that likely to get hit by a virus if you compute alone.

On a network, you're more likely to catch a virus. A network is to a computer virus what a day-care center is to a cold: the perfect place to spread.

If a virus hits you, it can waste a lot of your time. And you probably won't even know it's a virus when it does hit. You'll discover that the latest version of your important report is missing some paragraphs. Or you'll try to print a chart you need by lunch, and it just won't print no matter what you do. You might think you're issuing the wrong command or that your network is "acting up" again or that your printer is on the blink. And that could be what's happening. But sometimes it will be a virus -- an insidious little program that automatically copies itself to your disks from your network, from files you download or from new disks you slip into your floppy drive. The virus hides and intentionally or unintentionally trips up your computing.

Anti-virus programs have several parts. They scan, checking your disks for known virus patterns. They intercept, scanning any new disks for viruses before giving them access to your system. They immunize, preventing any program from altering your files or your system without your express consent. And they destroy, clipping discovered viruses from the files on your disks. Because new viruses appear constantly, produced by vicious and childish programmers, a good anti-virus program also needs regular updates to recognize the latest germs.

Anti-virus utilities for personal computers and compatibles differ greatly in speed, ease and options but little in their recognition of viruses.

Dr. Solomon's Anti-Virus Toolkit 3.5 (S&S Enterprises, $91.25, international phone number 0494-791900) is the worst of the bunch. Updates cost about $60 a year (the price is in pounds). The manual is certainly interesting, with historic details on lots of viruses -- with fascinating names such as Amoeba, Black Monday, Burger, Christmas, Dark Avenger, Devil's Dance, Fellowship, Frere Jacques, Jerusalem-B, Paris, Perfume, Sorry and Yankee Doodle.

This truly is a "tool kit," packing dozens of individual utilities for scanning and disinfecting. These programs do what they claim. But they are slow -- taking 10 minutes to scan a disk when the competitors need only a minute. And they are complicated. Only programmers should consider these tools, perhaps as an education in the parts that go into virus detection and eradication. Anyone else should avoid it like the flu.

The Norton AntiVirus 1.0 (Symantec, 408-253-9600, $129.95) comes from a company famous for its PC utilities and for a fine Macintosh anti-virus program, SAM (Symantec AntiVirus for Macintosh). This utility needs at least DOS 2.1 and 384 kilobytes of random-access memory. It scans, intercepts and eradicates. When the 24K intercept part in memory detects some tricky "viruslike" activity going on, it sounds an alarm noise and stops the operation.

The other part of the Norton AntiVirus is the Virus Clinic, which finds and fixes infected files. It is easy to use and install -- with menus for everything. There are several levels of operation, from simpler and faster to more thorough and sophisticated. It shows you how scans are proceeding and keeps an "audit" memory of all that it does. The Norton AntiVirus is quick -- scanning nearly 20 megabytes in about a minute -- but some reports say it does not catch every possible virus.

The Norton AntiVirus has the right support: for local or network disk drives, for CD-ROMs and removable disks, for DOS and Windows. It even scans programs already in memory. It recognizes a gross (144) of common and uncommon viruses. And it has superb update features: You can type new virus definitions in from your own information or as provided by Symantec, or you can download new virus information from a bulletin board.

Virex-PC 1.2 (Microcom, 919-490-1277, $129.95) works on PCs or compatibles with at least DOS 2.1 or later and 512K RAM. It recognizes more than 137 PC viruses and can clip those away from your files. Like the Norton AntiVirus, it can inoculate your computer against typical virus attacks with a 30K program that sits in memory, popping up a warning on screen when anything suspicious happens. It works on hard disks, floppy disks and network disk drives.

The Virex installation program can be more confusing than that of the Norton program because it asks many questions about options. For example, it asks if there are files you want to omit from the scan and if there are certain computer operations you want to recognize as virus attacks. These can be useful customizing tools if you're a PC pro; they're disconcerting if you're not.

Microcom provides $25 quarterly updates to cover new viruses or a $75 annual service for all such updates and any enhanced versions of the program. That's not as immediate or as inexpensive as Norton updates.

Virucide (Parsons Technology, 1-800-779-6000, $49) recognizes more viruses (more than 240 at latest count), costs less than half as much, installs most easily (though the Norton AntiVirus equals it) and needs only 256K of RAM (less memory than the competitors) and DOS 2.0.

Virucide scans floppies, hard disks and network disks for the viruses and lets you choose to remove automatically any discovered viruses and to keep a report on what's been done. It runs at about the same speed as the Norton AntiVirus and Virex-PC.

There's help information throughout and simple menus to set the options. The latest version -- 2.0 -- comes with a reference file that describes and explains all of the viruses. Virucide upgrades appear every quarter or sooner if there are important new viruses to catch and are available at $15 to $20 or so.

The drawbacks of Virucide are that it doesn't "inoculate" your system by automatically watching for and blocking new -- both Virex and Norton provide inoculation -- and the updates aren't immediate, as with the Norton utility.

Get a virus fighter, particularly if you work on a network. Dr. Solomon's is just too hard to use. Virex-PC has lots of options for experts but can be confusing. The Norton AntiVirus and Virucide are my favorites. Norton has a great update feature and watches for virus activity.

Virucide is the least expensive and the easiest to use.

Phillip Robinson is an author of books and articles about computers and an editor for Virtual Information of Sausalito, Calif.