[Abstract] It becomes more common that powerful computer viruses infect PCs and servers easily since Internet has emerged. The quick evolution of virus types, from simple macro virus to Spam mail virus such as Melissa, to hybrid virus with cracker features such as CodeRed and Nimda, has driven enterprises or end users to severe security panic from time to time. Could pure antivirus companies survive under more complicated computer security requirement? The top 3 antivirus companies in the world, Symantec¡BNetwork Associates and Trend Micro, according to Gartner Group¡¦s research, adopt different strategies to face strict security challenge. NAI fell from top spot due to its failure one-stop-shopping strategy, which now is executed again by Symantec. However Symantec becomes number one antivirus company in the world (IDC 2001 report). It turns out that the success DNA of antivirus company must contain innovation capability and vision. Trend Micro earns number three of world antivirus company based on her strong innovation and vision. Will Trend Micro¡¦s focus strategy ¡§Best-of-Breed¡¨ which is the major differentiation with other two competitors, Symantec and NAI, keep Trend competitive in the AV market? I will discuss this topic in this thesis.