I tried to update my iTunes to 8.0 and got the following error message:
There is a problem with this Windows Installer package. A program required for this installation to complete could not be run. Contact your support personnel or package vendor.
Following the recommendations on the Windows website, I uninstalled iTunes and tried to reload 8.0 and got the same error message.
I tried to reintall the older iTunes version which seemed to work until I tried to open it and got the following error message:

The file iTuneslibrary.itl cannot be read because it was created by a newer version of iTunes.

I tried to find this file but a search of my hard drive did not find this iTuneslibrary.itl file.

Any help would be appreciated!

Thank you

Follow the steps in bold here.