You can...
However, the better way would be to let iTunes do that for you, if you are already letting it manage your music (i.e. the default setting).
With both drives mounted, go to iTunes>Preferences>Advanced>iTunes Music folder location and click "Change..." Point it to the new, larger drive and click "Okay." It will take awhile to update your iTunes library. After that is done, click on "Yes" when it asks you if you'd like to move and rename the files.
This will help you avoid ! errors.