The Highly critical Secunia Advisory of 2006-12-19 is not a problem, FireFox 18.104.22.168 has been released in few hours !!!
You don't need to download this new version if you have auto update feature enabled because your FireFox will update by itself in a "couple of seconds".
I wonder when Microsoft Internet Explorer released an multiple patches update the day after after and then I wonder why You've not yet installed FireFox on your Windows, Mac or Linux computer!
This is quite a record for a browser and this is the complete FireFox 2 veulnerability report ... just 2 vulnerabilities and just one of them unpatched and it's a less critical problem.
This is "your" Internet Explorer 6 vulnerability report and this is the last version 7 of, again, Internet Explorer Browser vulnerability report with 3 bugs, one of them moderately critical and any of them patched.
So c'mon guys, what are You waiting for ? GetFirefox ;-)