From MozillaZine Knowledge Base
Internet Explorer is the most widely-used web browser and it is included as part of the Microsoft Windows operating system. Mozilla browsers such as Firefox have recently gained significant popularity over Internet Explorer, one probable reason being the publicity generated by Internet Explorer security flaws. Also, some appreciate what they see as the greater simplicity and efficiency of Firefox. Others continue to support Internet Explorer because certain sites, especially those dependent on Microsoft's ActiveX technology, reject all browsers except Internet Explorer. Some of these sites can be visited anyway via user agent spoofing, if a Mozilla browser extension such as user agent switcher is used.
If you no longer wish to use Internet Explorer
The easiest route would be to make your Mozilla browser the default browser and simply stop using Internet Explorer. You can also consider these other options:
Secure Windows and Internet Explorer
The SANS institute recommends the following precautions for Windows users. Remember that parts of Internet Explorer can be used by other programs, so users should follow the advice even if they don't click on the blue e.
Hide the Internet Explorer icon from the desktop
Right-click on the Desktop -> click Properties -> Desktop -> Customize Desktop -> Desktop Icons -> Internet Explorer <uncheck this
Another way (in Windows XP, possibly different for other versions of windows) Start -> Set Program Access and Defaults -> Add/Remove Windows Components -> Uncheck Internet Explorer -> Click Next. Now Internet Explorer has been partially uninstalled.
Remove Internet Explorer from Windows
Although uninstalling Internet Explorer from Windows is possible, you are strongly advised not to remove IE, for a number of reasons :
If you still want to remove IE despite these warnings, there are third-party programs available like LitePC that remove IE but these are most definitely not recommended for novice users. Instead of uninstalling IE, you should consider the alternatives first, such as making IE more secure, or hiding Internet Explorer.
Upgrading Internet Explorer
Internet Explorer 8
The following applies to Windows XP and Windows Vista
Internet Explorer 8 can be installed as an upgrade on Windows XP and Windows Vista . Visit the Internet Explorer 8 Home page and IE8 FAQs page for additional information. Windows 7 comes with IE8 preinstalled.
It is important to get the latest updates to your software. One easy way to get the latest updates is to set up Windows Update to download and install the latest operating system patches, Internet Explorer patches, and drivers.
Windows Update will not install the latest plugin software. You will have to manually update all plugins. Remember that Internet Explorer uses ActiveX plugins and all other browsers use Netscape plugins. If you wish to keep Internet Explorer and another browser up-to-date with the latest plugins, you will have to download and install both versions, and check that each browser is using the latest versions of plugins. You can check that Firefox plugins are up to date at the Plugin Check.