Internet Explorer unprotected for 78% of 2006

Or 284 days, according to a vunet piece, quoting the Washington Post:

"This included at least 98 days in which no software fixes were available to plug browser flaws that were actively being used to steal personal and financial data.

In comparison, Mozilla's Firefox browser had just one nine-day period last year during which a serious security hole went unpatched."

Another good reason to use Firefox? It's not security alone that should draw you to that conclusion - its superior implementation of tabbed browsing, plug-ins, speed of downloading pages, general UI ...