For years, Microsoft IE has long "allowed" and displayed html code that was not in W3C standards. Microsoft being Microsoft (the majority), has always had a tendency to do what they wanted.
Back when Netscape was still strong and had a significant portion of the market, I used to code websites. YES, as a coder, I always checked to make sure that my site worked and looked right in both browsers. I consider not doing this to be the fault of the coder.
Firefox is much like Netscape (same kernal) in that is represents and displays html exact according to W3C standards.
I use Firefox for everything possible because it is more secure. Only for certain sites that require some Active X controls will I use Microsoft IE (only sites I trust).
