Garminfone and iTunes
Want to port your iTunes library into your Garminfone so that you can listen to your favorite tunes on the go? Whether you're using a Windows-based computer or Mac, it's possible. And even better than that, it's quick and easy to do. The "iTunes Agent" for Windows users and "iTuneMyWalkman" for Mac users is all you'll need. Here's the step-by-step process for Windows-based computers.
1. Download and install iTunes Agent (or iTuneMyWalkman if on a Mac). You'll now see it in the system tray.
2. Plug the Garminfone into your computer's USB port and select transfer files
3. Create a folder in the Garminfone called Music
Next, you'll need to configure iTunes. Learn how to do that here so that you can successful transfer your files to your Garminfone.
Source: Garmin Blog