When you install iTunes in a computer running Windows Vista, you may receive the following error:

iTunes could not be installed because Visual Basic Script (VBScript) is not installed or has been disabled. Make sure VBScript is installed, turn off script blocking in anti-virus and personal firewall software, re-register VBScript, and then install iTunes.


iTunes official knowledgebase states the following:

If you see this error, it may be because the Windows Installer technology is unable to process the Visual Basic Script embedded inside the iTunes and QuickTime Installers.

For more information, read the article: iTunes and QuickTime for Windows cannot be installed without Visual Basic Script (VBScript)

In Windows Vista, you'll need to register the module vbscript.dll from an elevated Command Prompt window. To open an elevated Command Prompt, click Start, click All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

Type the following in the Command Prompt window and press ENTER

regsvr32 %systemroot%\system32\vbscript.dll

And then type the following to exit the Command Prompt window.