If you encounter error messages while installing iTunes with/or Quicktime such as “"the installer encountered errors before…" here is a solution for you:
Open iTunes installation file with an archiver program such as 7zip. (File / Open Inside, choose iTunes.exe)


Extract two files from the iTunesSetup file; QuickTime.msi and iTunes.msi, and save them in a local folder.

Open a command prompt window (Win + R -> cmd), navigate to that folder, and run the following command:




”Quicktime.msi /passive“

After you completed installing quicktime, open command prompt again, navigate to the folder where  iTunes.msi is and run
“iTunes.msi /passive”
command.

That also will save your time from uninstalling AppleSoftwareUpdate, AppleMobileDeviceSupport, Bonjour and MobileMe.

Update: You can get the latest itunes only installer from here.

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