How do I move all my itunes library from my PC to my new Macbook Air?

I have around 400 songs on my PC in my itunes library and i would like to move all of those songs to my new macbook air. I would like to do this because my PC is very slow and old and I would love to have everything on one laptop. My real question is if I the apple support team would be able to do this conversion for me if I would be to bring both laptops to the apple store, or it I would have to purchase a mac and PC compatible external hard drive to convert the music.