To move or modify your music folder(s), but not lose your precious Last Played and Play Count data, empty the itl file, move what you like, modify the XML file and restart iTunes. It will (re)import the XML file, but (unlike the normal import) WITH the fragile data.
More details here
dfbills adds: I haven't tried this. The example is on a Windows system.
On a Mac, I've kept my audit data by simply moving the iTunes Music Library and iTunes Music Library.xml files from one user account to another. You have to be careful to move your music as well, and if you want to put your music elsewhere, like on an external hard drive, open iTunes and change the path to your music files in iTunes > Preferences > Advanced before you do anything else.
On a Mac, I've kept my audit data by simply moving the iTunes Music Library and iTunes Music Library.xml files from one user account to another. You have to be careful to move your music as well, and if you want to put your music elsewhere, like on an external hard drive, open iTunes and change the path to your music files in iTunes > Preferences > Advanced before you do anything else.