Currently Being ModeratedSep 12, 2013 11:27 AM (in response to ukzdaly)
Thank you for using Apple Support Communities!
It sounds like the iTunes program downloads ok, but the installation fails toward the end.
I found this article for you to help troubleshoot the issue:
Trouble installing iTunes or QuickTime for Windows
Follow the General Troubleshooting first, then the Additional Troubleshooting if needed.