Expanding Itunes Library disk space.

My Itunes library will shortly exceed 3TB with loads of TV series and movies. I would like to know if the best solution would be to buy a second drive then move my TV series collection to it and have space on both but then how do I operate Itunes with multiple drives? Alternately I was thinking about getting two 3TB drives and formatting them as dynamic drives as I believe you can configure two drives or more to look like a single large drive to Windows 7. Will this work and will it work to store an ever expanding Itunes library. Thank you.