The Windows Vista Application Compatibility Update is a software update that addresses common application compatibility issues in Windows Vista. Microsoft regularly releases Windows Vista and Windows Server 2008 Application Compatibility Updates,” Microsoft revealed. “This software update is a prerequisite for Windows Internet Explorer 8. This update helps improve reliability when you install and use Windows Internet Explorer 8.
Applications that are included in the December 2008 update: Windows Internet Explorer updated to improve functionality; Microsoft Zune Software - hard blocked when you upgrade from Windows XP to Windows Vista; Kaspersky Internet Security or Anti-Virus versions up to version 7 - hard blocked when you upgrade from Windows XP to Windows Vista, Microsoft added.