How to Prevent Internet Explorer 8 from automatically installing on computers running Microsoft Windows XP, Windows Vista, Windows Server 2003, and Windows Server 2008.

Add following to the registry (see Figure 1)

Keys: [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Setup\8.0]

Value Name: DoNotAllowIE80

Data Type: REG_DWORD

Value: 1

Figure 1