to save your itunes completly liek how it is you firts have to make sure that you had your itunes set to copy all songs you add into the itunes library, instead of having them all over your comp. if you haven't done this then you go to prefs->advanced then click keep itunes folder organized and click add imported songs to itunes library.
now go file export library....this will generate and xml file of all of your songs titles/ratings/ and anythign info on them you have added ( if you have not added any info liek artist ourself or genre yourself there is no point in doing it cuz it will still have all of the old info.) nooooow you copy you itunes music folder and put it somehwere else on your computer along with your new library.xml file.