Hello krizely,
Thank you for providing the details of what you are experiencing when trying to download and install iTunes. I found an article with steps you can take when experiencing an issue like this.
I recommend following the steps in the article below when you are not able to install iTunes:
Trouble installing iTunes or QuickTime for Windows
http://support.apple.com/kb/HT1926
Thank you for using Apple Support Communities.
Best,
Sheila M.