I downloaded I Tunes to an older HP desktop that is running XP with service pack 3. There's plenty of free space on the hard drive, and there is 1 meg of RAM. The .exe program installed the program with no error messages. I connected an iPad to the computer with a cable to a USB port on the control panel. When I tried to upgrade to iOS 7, I got an error message saying that the computer was not connected to the internet. I found and ran a diagnostic which showed that the internet connection was active and that iTunes had made the connection, but that it was not possible to establish a secure link to the I Tunes store. How can I get this last step of the connection done? Thanks much.