ScanIT, a web consultancy company, is showing statistics reflecting that Internet Explorer was unsafe for 98% of 2004, verses 15% for Mozilla based browsers like Firefox. This puts to rest arguments that Internet Explorer is a security problem only because it is more popular at the moment. The Inq article is well worth reading as it explains some of the reasons why, and the implications of, the IE security problem.
Run the browser security checker yourself at http://bcheck.scanit.be/bcheck/ to find out if your protected, I just ran the test myself using Firefox and it found zero known vunerabilities. Good to know.