Do a search for reported vulnerabilities for IE and one for Netscape/Mozilla.
I think by count alone IE will win. My biggest issue is that with a locked down system, IE can still install malware, when the user can't even install system patches. If MS could fix that, there would be fewer issues. But then they would have to break the hooks between the browser and the OS. _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
