An error occurred during installation of assembly ‘Microsoft.VC80.CRT, type=”win32″, version=”8.0.50727.6195″, publicKeyToken=”1fc8b3b9a1e18e3b”, processorArchitrcture=”amd64″
First try this:
Control panel -> administrative tools -> services -> Windows Modules Installer -> switch to Automatic from Disabled
If this doesn’t help, simply download and install this component, and after that, iTunes installation should be fine. Click the download link.