Apparently none of you read his post.
From a web developer .... Some content management systems that were created a long time ago only have wyswig editors that work with explorer. The reason being is that they were created before the popularity of other browsers. This caused the person writing the script to write hacked up code that would work in IE. The amount of shit that took place caused them to not want to develop for other browsers and there for making the code browser specific. Sometimes you can get away with making firefox or safari simulate being IE. I had a website I used to work for that I could do this with. But, the editor still didn't work so it ultimately caused me to instal IE6 onto my mac.
Installing IE6 onto a mac is entirely doable. You use Darwin/Wine to make it happen. Everything works pretty much the exact same as it would on a pc. You even have to use ctrl instead of command.
And to all of you saying firefox is the best... it's entirely relative to what you are trying to do. Firefox is actually a bit of a pain in the as from a developer standpoint in that it requires mox- infront of pretty much all css3 causing additional lines of code that IE 8/9, Safari, Opera, and Chrome dont need. Sweet, IE6 is virtually dead, but now i need to develop for firefox instead. Awesome!
As far as security goes, firefox is better. As far as rendering web graphics, safari was better, now firefox reads color profiles the same. It only took them about 6 years to catch up with that one. Speed, it's pretty equal now. Safari handles errors in the script better than firefox though, so sometimes a page takes a little longer to load, but it will process better.
So, if you are a casual internet browser that does their taxes online, firefox is better if you really care. If you are a developer or doing lots of forms and so forth, safari/chrome are better.
In the end, OP, google, instal internet explorer on mac with wine. You will find the answer.