Consolidating itunes folders
To consolidate libraries, turn on Home Sharing for all the computers you want to merge and then drag and drop the files to the computer that will store the merged library.
You'll find the shared computers in the left-hand column of i Tunes.
Select the folders that you want to move from the i Tunes Music folder (usually the entire folder, unless you want to select only certain artists/albums) and drag them to the "Library" section of i Tunes.
Also you can drag files either from Windows Explorer or MB's main panel while holding control key and drop to a folder.
— are stored in your i Tunes library, not just music.
You can find these non-music items in your i Tunes folder (in the My Music folder).
If you use an online backup service, merging i Tunes libraries can be as simple as downloading the latest backup from one computer to another (if your library is very big, you may want to use DVDs with your data on them that some services offer).
All the contents of your i Tunes library — apps, movies, TV, etc.