I installed iTunes 8 on my laptop yesterday and found that I could not see the content of my desktops iTunes library, which is still on 7.7.1. The library still shows up in the sidebar, but no content. Now I'm at work and the same here, I can only see songs in one of three libraries (Have to find that guy and ask him if he updated). So, iTunes 8 is not compatible with iTunes 7? That sucks!