Changing PC and transferring all iTunes data?

I have a PC for managing my iTunes library but it's on its way out and I've now bought a new PC to do the job.

I understand there is a library.xml file I can copy over to retain all the Song/Artist/Album titles, ratings, playlist etc.

My only concern is that the .mp3 files are not in one single folder, but rather split between several dozen folders in my PC's C:\ directory.

How can I locate every folder that contains .mp3's in my iTunes library? The PC OS is Windows 7 and the iTunes version is the most up-to-date version.