I can't test x64 installers but it seems like it could be a failed installation of an earlier iTunes version. Uninstall iTunes and download Microsoft Windows Installer Cleanup Utility from here. Then, try to install my switchless installer and see if it works well this time. Don't forget QuickTime Alternative and its iTunes Add-on too. On 32 bit machines QuickTime Alternative + Add-on works fine with iTunes 8 but on Vista x64 it doesn't work . I'll try the clean up utility Hm okay well it seems like the problem was that I didn't restart the machine after installing. The switchless then works fine and so does QT Lite + Add-on cheers!