I have to disagree with the majority of the users posting in this thread. Firefox really doesn't have a place in the business world. When you look at a business as a whole it is made up of less technical savvy users. Yes there are a few exceptions to this rule (especially when I developed a report and used some small features which were accepted by Internet Explorer but not Firefox). When you look at Firefox and its "extensions" although these are easily added by clicking a link a ZAP installation can be created to push any ActiveX control needed to each PC so that the there are no issues with Internet Explorer and installing these controls.
If Internet Explorer is configured properly there is no reason why it cannot be used in a business sense. People like familiarity they don't necessarily like change. Changing their browser may cause more confusion then it is worth.
I agree 100% with Jeronimo, I am an avid user of Firefox (it is the first application I install after a reinstall of the operating system) however for the case and question at hand Firefox really doesn't belong in the corporate world -with a few exceptions.
Good article to read:
Mozilla Firefox vs. Internet Explorer: Which is Safer?