* Many web sites are programmed to work only with Internet Explorer. For example, webmasters authoring a site may have not tested with other web browsers. Some webmasters may not be familiar with WC3 standards or taken the time to program their site so it is universally acceptable by all browsers. Probably 95% of all websites on the Internet should work with Mozilla browsers, but there it a site is not compatible it may appear distorted or inaccessible unless IE is used as a browser.
* Windows Update (WU) requires Internet Explorer. As an alternative, you may be able to manually download security updates, but it will require more monitoring and work than letting WU handle this for you.
* Some Anti-Virus Products require IE for updates. Live updates or automatic DAT updates used by both Norton and McAfee are built on Internet Explorer's foundation. You may be able to manually update your virus signature files but it could require more work.
* Both removing and restoring IE is risky and difficult. IE is complex with extensive hooks built into Windows, for efficiency and functionality. Thus unplugging it from your system may impact Internet connectivity, Windows functionality, and break functionality in Microsoft Office and non-MS products.
* IE is more than a browser, it is the foundation for Internet functionality in Windows. If you compare the install base for Internet Explorer 6 (43.5MB) to Firefox (4.5MB), it provides an indication IE is more than just a browser.