Sorry, finally found the post I was thinking of and it's not actually the solution for the issue you're having. However, assuming you really did move absolutely everything, I'm pretty sure all you need to do is just highlight everything in your current iTunes, right click and choose Delete to remove them from the Library, then go to Preferences > Advanced and change the location of the library to your new drive.
I have to point out, I've never done this, but from what I can see it should work. I think you may lose your playlists though. Might be better to wait till tomorrow when some of the more knowledgeable iTunes regular forum posters are on and see if there is a better way.