Acting with record speed, Microsoft has issued a patch for the just-announced security flaw that impacts all recent versions of Internet Explorer, from version 5 to the latest betas of IE 8. The next security update had not been due from the company until January 13, making this a very rare occurrence.Most scary? Up until now, I had thought Opera was a pretty good browser, it's certainly nice to use. It appears though that Opera was subject to the same vulnerabilities as it uses the same XML
If you're still using Internet Explorer for your browsing, really, it's NOT SAFE. No browser is completely secure, but IE is part of the core operating system of Windows, and when there are unpatched exploits, the attack can get directly into Windows itself. By far the safest way to browse is with Firefox, and it's probably tied after that between Apple's Safari and Google's Chrome. Opera remains a groundbreaking bit of software, but if the default behaviour is still to pretend to be IE and also open up vulnerabilities regardless, it isn't as good as it should be.
For the full security shield, Firefox has plugins such as Flashblock, Adblock and NoScript that really do push it to the top. At the very least, Flashblock stops system hogging flash from hijacking your browsing unless you want it to, it's the first thing I install after Fx on a new machine. Always.
Another part of this vulnerability involved Adobe's Acrobat Reader. PDFs are, unfortunately, now a part of life, and there are still many many idiots that put their PDFs online and think they've got a decent web presence. Given this, the PDF download plugin for Firefox is essential, and switching to a much faster and less system intensive reader (I use Foxit) for your default PDF setup is probably a good plan as well.
 I'm ignoring text only and other lite browsers such as Lynx here, just talking about normal, standard plays YouTube vids and looks normal browsers.