The Security Mentor

This isn't the only way to measure security and all the ways are infinitely arguable, but The Security Fix column added up how much time Internet Explorer suffered security bugs which attackers were using but which Microsoft hadn't patched. Those were days when IE users were helpless against attacks that bad guys were actively using.

284 days out of 365. The same number for Firefox was 9, mostly because of faster bug fixes as opposed to fewer bugs.

It's too early to tell how the new version of Internet Explorer will do, but Microsoft has made fundamental changes in many good ways. If you run IE, run IE 7.