Can UK players play with American players?

I'm gona be getting Guild Wars soon and I'v got a friend in the UK who I'v talked into joining me but I need to know if she needs to get the US version to play with me or if the UK version will let us play together.

I'm guessing she'll need to get the US version but I would also guess that Guild Wars would have a monthly fee and it dosnt. XP

You can play together in the international districts, or if your friend wants, she can make her "home world" the US district (or you can make your's the European). Also, you choose what world you want when you create your account. So it doesn't matter where you buy the game.

Thank you very much ^^