Your i Tunes library, a database that's made up of all of the music and other media that you add to i Tunes, is organized into two i Tunes library files and an i Tunes Media folder.
Before you back up your media, find the location of your i Tunes Media folder and consolidate your library.
Find the i Tunes folder on the external hard drive, and the i Tunes Music folder inside it.
More » If your i Tunes library comes primarily from the i Tunes Store, try this option.
Most don't transfer apps but, as noted above, you can always redownload apps to the new i Tunes library.
Unlike the external hard drive method above, these programs let you retain star ratings, play counts, playlists, etc. (If you don't, I'd recommend starting before a hard drive failure makes you sorry you didn't.
Among the key features of these programs are that they will retain all of the metadata--star ratings, playcounts, comments, etc.--that are lost using other transfer methods.
A few of the programs in this space include: If your entire i Tunes library is synced to your i Pod or i Phone, you can move it from your device to the new merged i Tunes library using third-party software.