Current anti-virus technology provides only sparse protection against the kinds of threats that Internet users face today. For more than a decade, anti-virus software has been a pillar of enterprise security programs. <A HREF="http://www.eweek.com/article2/0,1895,1871414,00.asp?kc=ewnws101705dtx1k0000599">But times are changing.</A> The explosion of current online threats could unseat traditional anti-virus technology and the companies that sell it from the front lines of computer defenses as users turn to more proactive technologies, experts say.