How do you transfer iTunes to Windows 8 when you use an external hard drive to store you music/media files

I've tried a number of different search terms and yet can't quite seem to find an exact answer to my question.

I currently use a Windows 7 computer and have my songs for iTunes on an external hard drive. I would like to find some step by step instructions on how to transfer my library to a new Windows 8 computer and still utilize the external hard drive to store my music. What I find very confusing is I have similar folders for iTunes on both my computer and the external hard drive (ex. Album Artwork, iTunes Library Extras, Previous iTunes Libraries). I'm not sure which files to move over to the new computer to make for a smooth transition.

Thanks in advance for your help. 🙂

Paul