Internet Explorer has been subjected to many security vulnerabilities and concerns: Much of the spyware, adware, and computer viruses across the Internet are made possible by exploitable bugs and flaws in the security architecture of Internet Explorer, sometimes requiring nothing more than viewing of a malicious web page in order to install themselves. This is known as a "drive-by install". There are also attempts to trick the user into installing malicious software by misrepresenting the software's true purpose in the description section of an ActiveX security alert. Better not to use it then.

• Install Firefox or other trusted 3rd party browser.
• Navigate to the Control Panel by clicking on Start, followed by Control Panel (or Settings and then Control Panel, depending on how you're setup).
• XP - In the Control Panel window, open Add or Remove Programs.
• Note: In Microsoft Windows XP, depending on how your operating system is setup, you may not see the Add or Remove Programs icon. To correct this, click on the link on the left-hand side of the Control Panel window that says Switch to Classic View. In the Add or Remove Programs window, click on the Set Program Access and Defaults button on the menu on the left.
• Vista - In the Control Panel open Programs, followed by Default programs then open Set program access and computer defaults.
  
• Choose the Custom option in the Choose a configuration: area.
• In the Choose a default Web browser: area, uncheck the Enable access to this program check box next to Internet Explorer.
• Click OK. Windows will apply your changes and the window will close automatically.

Remember: Even though you may be disabling Internet Explorer, you are not actually removing it. Your Windows PC still uses Internet Explorer for a number of internal processes.