The only real downside to developing websites on Mac OS X has been finding the right tools to test my work in Internet Explorer. I recently discovered a simple way to test IE from our friends at Tuts+.
RemoteIE is a free tool from Microsoft when you sign up for developer account (which is also free) and if you would like to try it out, I recommend getting started the way that I did by using the tutorial at Tuts+ that I mentioned earlier, called A Fast, Accurate Way to Test Internet Explorer on iOS, Mac OS X, and Android.
