I think I am not the only poor soul to meet this problem. OK, if you have seen

There is a problem with this windows Installer package,
A program run as part of the setup did not finish as
expected. Contact your support personnel or package
vendor.

then, you know what I am talking about. After downloading the Apple Itune package, I just can not install it. So stupid. Quick way to fix:

Control Panel -> Uninstall your QuickTime.

Yes, unintall your QuickTime not the Itune. Then you give it shot, you now should be able to install the new version of Itune.