+But still cannot "uninstall" from the control panel.+
Okay. In that case, let's try using the Windows Installer CleanUp utility to remove the installation configuration information.
download and install the Windows Installer CleanUp utility:
Description of the Windows Installer CleanUp Utility
Now launch Windows Installer CleanUp ("Start > All Programs > Windows Install Clean Up"), find any iTunes entries in the list of programs in CleanUp, select those iTunes entries, and click “remove”.
Quit out of CleanUp, restart the PC, and try another install.
If it doesn't go through, let us know what error message you get this time. (Fot example, is it now saying *Invalid drive* J?)