One reason to stay with Internet Explorer, despite all its shortcomings, is that you are familiar with its looks and feel. One of the wonderful things about Firefox (and Flock) is that there are many Firefox add-ons for it, including several that will give Firefox an Internet Explorer look and feel.
The first thing to do is to get a theme. There are many more themes to choose from than the two I mention below, but these will do the trick.
NeoFox is a theme that makes Firefox 2.0 look like Internet Explorer 6.
MyFirefox is a theme that makes Firefox 3.0 look like Internet Explorer 7.
Firefox is a modern browser that support all major web standards. It will let you view any web site, but some ostensible "web sites" aren’t web sites at all. Some are IE-sites that can only be viewed with Internet Explorer. The best known and most important offender is the Windows Update site. To view IE-sites without having to leave Firefox, install the IE Tab tab.
IE Tab shows IE-sits inside a Firefox tab, as if they were regular web sites. It works perfectly, because it actually relies upon Trident, Internet Explorer’s rendering engine, to do the rendering in a Firefox window.