I actually JUST moved all mine too and had the same problem. What I ended up having to do was delete the XML and all the extras files from the itunes folder completely, then import the XML with my saved playlists/imported playlists into itunes again, and it worked that times.

Like blueraccoon said above, you have to make sure the preferences are pointing to the right place, but it didn't work unless I did that FIRST, then deleted the XML it had created when I first opened the fresh itunes install, and then imported the correct one.