For future reference, the EASIEST way to move your music library in iTunes is to do this:
1) Back up your iTunes Library and iTunes Library.xml files, just in case
2) Set your iTunes Music directory to be the folder you want to put your music in (on the new drive, other partition, whatever)
3) Make sure "keep folder organized" and "copy music to folder" are checked
4) Choose Advanced > Consolidate Library
5) Make a sandwich, read a book, do some yoga
6) Yay, your music has been moved, and you've lost no metadata!