How to create copies of itunes files into itunes folders in order to backup

hey,

i want to back up my itunes library for transfer it to mt new windows computer.

how can i make a copy of files into itunes folders (with the organization i already made in itunes) after the option "copy files to itunes media folder when adding" was off? (when i turn it on now, it doesn't seems to make any difference- the files don't make a copy in the "iTunes Madia" folder...)

thanks

Reut