For those of you iTunes 7.1 users who are dismayed by the inability to display the entire library (as noted in this post) here's a workaround. Create a Smart Playlist whose only criteria is "Size is greater than 0" and click on Live updating. Name this new SP something obvious like "Everything" or "Full Library" or what have you. Then create a script like this, substituting the name of your SP where appropriate:
Save it to your iTunes Scripts folder and give it a shortcut so you can easily display the SP when necessary. Thanks to Correspondent George Dick for the idea.