Thanks for using Apple Support Communities. If you are unable to install the newest version of iTunes, I would recommend following the steps in this article:
Here is the version of iTunes you'd need:
Hi Not sure if you have solved this yet.
I tried to update to the latest version and it fails for a number of reasons, Can't find a dll/ no permission for particular registry location.
Tried all the recomended things, the one that finally worked was uninstall all apple products and Quicktime.
I am quite certain that the quicktime was the problem but I had un-installed all the apple stuff previously.
I then installed the latest version and although It then kept saying missing registry key it kept going and eventually finished installing and now working fine.