FairGame

FairGame will convert the songs you bought on the iTunes Store to an unprotected format (using iTunes default encoder) and keep all the original metadata, lyrics and artwork. It takes 2 min. 42 sec. to convert a 4 min. song to AAC on a MacBook Pro 2.16GHz.

What you MUST DO (only once) to get FairGame to work:
Enable Access for assistive devices in the Universal Access & system preference
select; Place clip in Movie Timeline in the Import & preference of iMovie HD

Then you can simply: select some songs in iTunes click on the Process button & then don't touch anything and wait until it's done...
(FairGame is scripting iMovie's interface to process the songs, don’t interfere)

FairGame