For years I used PCs without antivirus software installed. I was smart enough to spot dangerous attachment, right? Unfortunately, flaws in internet Explorer, Outlook, Java, and other technologies that dovetail with your e-mail program mean that a properly crafted e-mail message could install and execute a virus on your PC without much action on your part-all you’d have to do is read the message.

A virus (a malicious program file you download to your PC), worm (a program that sneaks onto your PC without a file download), or Trojan horse (a malicious program that piggybacks onto or masquerades as a legitimate program) can enter your PC in several different ways, but e-mail is the most common means of infection. You can pay dearly for a subscription to commercial antivirus programs. I have used used two freebies-Grisoft’s AVG Free Edition, and Alwil’s Avast 4 Home edition-for several years, with great results. The programs are unobtrusive, and they automatically receive frequent virus-database updates. Both also received a thumbs-up from antivirus testing outfits ICSA Labs and Virus Bulletin.