The essential difference between a virus and a worm is that while a virus spreads by infecting other files and cant operate on its own, worms can work as independent programs capable of propagating and doing damage without using other files. 

Importance of Updating: All of you must be aware what an antivirus is. Here, what we would like to emphasis is the available options for antivirus and the fact that you must keep them regularly updated.

Obtaining Antivirus: Antivirus programs that you could use for your PC can be obtained from the sources described in the 'top antivirus vendors' box presented in the right portion of this page.  Those companies mentioned in the box provide protection that can be bought on a CD from the street or over the Internet using credit cards. once installed, they can be used for scanning your PC at any point of time and for real time protection so that they actively monitor your system scanning files as your system opens files and as you open attachments that are part of the e-mails.

Today's latest antivirus programs do automatic updates to their engine so that they are capable of identifying the latest virus or worm that has come to life. Other things to remember is that these days when the scourge of spam and worm generated mails are so ubiquitous, it is best to not open and delete any mail that you don't feel like meant for you by the look of it. Spoofing of the from address (they come in the pretext that they are  from known people make this very difficult). However it is necessary to be a good observer to avoid jumping into a problem mail.