Ну так скопируй текст из гугла, в чем проблема?
http://en.wikipedia.org/wiki/Computer_virus
http://stason.org/TULARC/security/computer-virus-l/65-How-many-viruses-are-there-Computer-virus.html
http://wiki.answers.com/Q/What_was_the_most_destructive_computer_virus
http://www.answerbag.com/polls/virus-computer_1980671