How to transfer itunes from external hard drive to another external hard drive

Hi guys - I have all my videos, music and photos located on an external 1tb hard disk drive. I unchecked the copy to itunes box so that none of my data is duplicated again on my imac. So basically all my itunes, iphoto and music runs of my external hard disk drive.

problem is im nearing the capacity of the 1TB and am probably going to opt for something bigger. Perhaps a 3tb my book live.

Whats the best way to transfer my files from the 1tb external hard disk drive to the new 3tb ecternal hard disk drive without losing my itunes organisation and album art for music and films.

Any help would be greatly appreciated.

thanks friends 🙂