new version of itunes wont download.

Okay, so I keep trying to download itunes onto my computer, which is Windows Vista, and this message box keeps popping up say there was an error and to refer to help and support. I go there and it does not help me at all. When I try opening itunes it says that i need to uninstall and re-install itunes. I keep doing that and it says the same thing each time. I even tried downloading an older version of itunes and it still wont work. I''ve even went on this site: http://support.apple.com/kb/ts1717 and i've done everything it says and it still wont work. I am running out of options 😟 someone please help me.