After seeing the Vulnerability at http://secunia.com/advisories/12889/, I am almost convinced about to get rid of IE. But what to use? Alright, Firefox is hot topic. But what do you say to this comment? ( http://news.com.com/Firefox+flaw+sparks+a+fiery+debate/2100-1002_3-5517201.html)

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One reader even took issue with the claim that Firefox is inherently more secure than IE. "Firefox may offer some 'security through obscurity,' but once it gets to any sort of critical mass, then it will be targeted. Since the hackers have the source code, their lives will be that much easier, and when a patched version is released, it will be easy for them to see where the vulnerability is and target older versions," said one London-based IT worker.
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Yes, I too believe right now Firefox has the advantage "security through obscurity" that will decrease the same time its market share increase. However I do believe Firefox gets fixed much faster. As for the statement it would be easier to target Firefox because it's open-source, actually I don't know if that's true. I don't know how "evil hackers" work. i.e. if they are interested in reading the source, or if they just run certain tests agains the system (buffer overflows etc. – a buffer overflow usually means some piece of code was not programmed right, but if this would have been easy to see by someone, surely the original programmer would have fixed it or not done it in the first place – and wouldn't this mean the security hole is hard to find? I don't know for sure.)

Don't forget that Firefox and all other Gecko based browsers run in a "sandbox" which isolates them from the OS, IE is so integrated it cannot be fully removed.