beatle888 said:iTunes files a copy of the mp3s so after doing what Gee said to do in the above quote you can go ahead and throw away the copy that you actually dragged to the iTunes icon.
Since this topic originally started with iTunes on Windows, I would like to warn that poster NOT to delete those files on the PC. iTunes imports the tracks if you drag the folder into the iTunes library window, but it does not copy them to the PC iTunes library.
You can safely delete the original files on the PC if you have enabled the "copy to iTunes folder when adding to library" function, which was disabled by default when I last installed iTunes on a PC. It is available under Edit>Preferences>Advanced (check box near the bottom).