You are allowed up to 5 computers with your i tunes account. If you have an external USB Hard Drive, I would first install a new i Tunes programme on that. On your old PC, using Windows Explorer, copy iTunes to it. This is not the actual programme files. but contains all your other stuff.then on the new computer open i tunes, then in music, select add folder to the library, then highlight the i tunes music folder on the USB HD.