The music library could be problematic. There are a few apps available for Android that will read an iTunes playlist, but there are no good alternatives that I found when I was using an Android phone. You can manually drag-and-drop your music to your Android phone. That's as good as it got for me. Apps like Double Twist purport to sync iTunes playlists, but I personally didn't have much luck with it.
Your contacts could be easier, depending on where they are stored on your iPhone. If they are stored on the PHONE itself, you can probably manually export them and import them on your Android phone. If your contacts are stored in Gmail or Hotmail or whatever service you use for that, they should sync right over with little manual intervention required.
We went through this last year when we replaced our Android phones with iPhones. Only about half of our contacts rolled over. It turns out that Google stored contacts in multiple contact lists. Some were on the phone itself, some were in Gmail itself, some showed up in Gmail on an "alternate contact list"... It was a real mess.