as long as you were organized to put everything into the appropriate "My_____" folder just open explorer and on the left side of the screen (where it shows library as a folder) rt click on library and select copy, then paste it to the new drive. This is about the easiest way I can think of off the top of my head.
Edit - just be prepared for explorer to go to a 'Not Responding' Status. it always does during long file transfers like that. Just let it run and run. You might want to break itup into smaller moves by doing 1 subfolder at a time. Copy music, later copy documents,... etc.