Jason,
Do you have an iTunes folder on the other drive? Does it contain a file called "iTunes Library.itl"? If so, that is your key library file. It contains all the information iTunes needs to start as you are used to seeing it. You do not point to that using preferences. All that changing preferences will do at this stage is tell iTunes to start storing any new media there. You tell iTunes to use that file by starting iTunes (as said earlier) while holding down the option key and tell it to use that library.
If you do not have that file anywhere then your library got lost in your rearrangement. All you have are a bunch of media files and you will have to rebuild your library from scratch.
What are the iTunes library files? - http://support.apple.com/kb/HT1660
More on iTunes library files and what they do - http://en.wikipedia.org/wiki/ITunes#Media_management
What are all those iTunes files? - http://www.macworld.com/article/139974/2009/04/itunes_files.html
Where are my iTunes files located? - http://support.apple.com/kb/ht1391
iTunes 9 [and later]: Understanding iTunes Media Organization - http://support.apple.com/kb/ht3847 - plus supplemental information about organizing to new structure https://discussions.apple.com/thread/6477809?answerId=26404702022#26404702022
Image of folder structure and explanation of different iTunes versions (turingtest2 post) - https://discussions.apple.com/docs/DOC-7392 and making an iTunes library portable.