Microsoft wanted their customers to become more secure and up-to-date, Microsoft will distribute Windows Internet Explorer 8 as a high-priority update through Automatic Updates for Windows XP Service Pack 2 (SP2) and higher, Windows XP Professional x64 Edition, Windows Server 2003 SP2 for x64 and x86, Windows Vista for x64 and x86, Windows Vista SP1 for x64 and x86, and Windows Server 2008 for x64 and x86.
If you are a organization and like to block the automatic update to Internet Explorer 8, you can go for Blocker Toolkit.
This Blocker Toolkit is intended for organizations that would like to block automatic delivery of Internet Explorer 8 to machines in environments where Automatic Updates is enabled. The Blocker Toolkit will not expire.
The Internet Explorer 8 Blocker Toolkit enables IT Administrators to disable automatic delivery of Internet Explorer 8 as a high-priority update via Automatic Updates and the Windows Update and Microsoft Update sites.