Firefox is far, far quicker than IE. It's also regarded as more secure (although IE is, reportedly, catching up with Firefox). As part of that security, Firefox deliberately doesn't recognise certain types of coding for web design (because they could be used for malicious purposes). So the 'Refresh' function, on the 'Recent posts' box of this page, won't work with Firefox. (Otherwise, AB loads perfectly well).
Firefox is also far more flexible, with a wide range of add-ons available. It's the browser of choice for most of the 'regulars', here in AB's Technology section.
Chris