I never thought of that before, it acctually sound like a really good idea. IE9 seems to be safer than other browsers right now but that can change. Opera is deffinetally the most malware-prone browser.
Using Opera for years and I never got any infection whatsoever in my browsing experience using Opera...
Of course Opera didn't stop me frow downloading malware, but it happens because I'm deliberately downloading it for my own malware collection.
The same goes for Firefox and IE. I use it for years and almost never got any infection by using it (I rarely got hit and when it happen I have my antivirus blocking, intercepting, or cleaning it).
So, any browser is malware-prone browser only if it being used by malware-prone user...
