If you’ve ever tried to use your iTunes music in Windows Movie Maker, you know what a hassle it can be. The purchased stuff won’t work, and the stuff you ripped from CD very possibly won’t work either. There are two ways around this:
Re-rip your CDs as MP3s and then import iTunes tracks into Movie Maker
Any way you look at it, iTunes and Movie Maker don’t work well together unless you take some extra steps.