But you should have at least one more of the above checkers as a 'second opinion' and a back-up. Some antivirus programs check on start-up, some check when you place a new disk in your floppy drive, and some check at regular intervals which you can adjust yourself. Some can be set to do all of these checks. Anti-virus developers will offer regular updates, either by mail or by download from their Web sites. In some cases, you just have to update the data files and, in others, you have to replace the whole program.
Most antivirus updates install automatically.
It's definitely worth taking the time to update. New viruses are found every day. A Kid's Guide to the Internet's World Wide Web .