If they have been Added to iTune's library, then you can move those files out of LW's dwnld folder for backup or even delete them. But keep in mind, that although there's a LW playlist within iTunes, it is purely a reference to the files in the LW Dwnld folder. To add them to iTunes library you can use the Control & O keys or drag & drop the files onto iTunes application. It will then import them into its own library. Best way to find out is to check iTunes library compared to LW's downld folder.
To access your LW downld foler files quickly, go to LW's library & click onto Saved Files & click onto one of the files to the right of it & then press the browse button. This will open the folder up for you.
An iTunes Tutorial:
http://www.apple.com/support/itunes/...ial/index.html