How many times have you heard a comment like this: "My computer is acting up. It must be a virus." Truth is, most computer glitches are caused by software conflicts or "user error."

Viruses do get a lot of publicity, and it's easy to see why. They have an ominous and mysterious aura. How can a machine catch a virus? Can computer viruses, like such human viruses as HIV, be deadly?

Computer viruses are simply small computer programs that aim to do harm. They're written by disturbed individuals, the kind of sociopaths who place razor blades in apples at Halloween. Like human viruses, computer viruses can replicate, spreading like a disease from one computer to another through shared floppy disks, infected CD-ROM discs or over the Internet.

Some viruses - more hoaxes than true viruses - are innocuous, doing no more harm than scaring people with a message flashing on screen that reads "Gotcha!" Other viruses, however, can destroy all the data on your hard drive.

Computer viruses can't harm your hardware. So the first line of defense, as with every potential computer disaster, is to make regular backups of the vital data stored on your hard drive and to ensure that the backups themselves are reliable.

The next safety step is to consider using antivirus software. Some people suspect that new viruses are created and spread by the very companies that develop antivirus programs. After all, there's a lot of money to be made here.

Sales of antivirus software reached $135 million in 1998, according to estimates from the market research firm PC Data. According to Ziff-Davis Market Intelligence, five of the 10 top-selling utility programs are antivirus packages.

Virus-protection developers do what they can to keep viruses in the mind of the public. A survey last year by the National Computer Security Association indicated that 99.33% of medium-size and large organizations in North America have experienced at least one virus infection. Every year, on average, four out of every 10 computers in these organizations become infected.

That sounds dire indeed. But who paid for the survey? Virus-protection companies.

It should be pointed out that the National Computer Security Association includes as one of its aims the promotion of ethical practices among virus-protection companies. So far, there's no evidence that a virus-protection company has ever let loose a virus it was studying in its labs.

What's more, despite the sensationalism, investing in an antivirus program is still a prudent course of action. It's especially important if you do a lot of program downloading or otherwise try out lots of new software, if several people have access to your PC, or if your PC is part of a local area network. Whether you buy an antivirus program or not, don't become paralyzed by fear of viruses.

Some people avoid the Internet entirely for fear of catching a virus. A few words of reassurance: Your computer can't become infected by reading email messages. Viruses, as programs, must be run, or "executed," to do their damage. Simply reading an email message doesn't run anything except the programs you already have on your system.

The situation becomes slightly more complicated with email attachments. These appendages to email messages can potentially include "macro" viruses, which can infect your system and are the fastest growing type of virus. But you have to initiate action beyond just reading the email message, such as clicking on the attachment with your mouse, for these mini-programs to do their dirty work.

Fortunately, you have protection here as well. Many people simply delete email attachments if they come from someone they don't know. What's more, the latest versions of antivirus programs include protection against macro viruses.

It's theoretically possible for your system to become infected with a virus by visiting a Web site whose creator coded in land mines in the form of malicious Java applets or ActiveX controls. But there have been no reports of such sites, and if one did appear, it would be shut down quickly.

Along with curtailing your activities, the threat of viruses can also make you scramble needlessly. If you receive an email message warning about a hideous-sounding virus, it might be a hoax. The U.S. Department of Energy has created a Web page at ciac.llnl.gov/ciac/CIACHoaxes.html that describes virus and other Internet hoaxes. Another good virus hoax site is Computer Virus Myths at kumite.com/myths.

Still, virus infections do occur, and they can cause considerable damage. Norton AntiVirus is the best all-around antivirus program, though McAfee VirusScan has many loyal supporters as well. Both cost less than $50 for the single-user versions.

Finally, be careful. Download files only from reputable Web sites or FTP file repositories. Avoid "pirate" sites and the "Warez" newsgroups, where people illegally trade commercial programs. These files are more likely than others to be infected with viruses. ?

Reid Goldsborough is a syndicated columnist and author of the book Straight Talk About the Information Superhighway. He can be reached at reidgold@netaxs.com or members.home. net/reidgold.

The VantagePoint Network, Ft. Collins, CO, has launched its Internet-based crop management and recordkeeping system.

Available at www.vantagepoint.com, the site provides information and services that enable farmers to keep crop records, track grain storage and sales, and communicate with their advisors when making agronomic, management and marketing decisions.

"The need for comprehensive and accessible documentation of production agricultural practices is becoming increasingly important," says Greg Holzwarth, VantagePoint's CEO. "VantagePoint subscribers will have more opportunities to increase the value of their outputs as we add features and as the market for trait-specific and identity-preserved outputs expands."

VantagePoint is a joint venture of Deere & Company, Farmland Industries, and Growmark, Inc. F