mac OSX and pc XP compatible?

I'm trying to get a group of players together to play civ. However, one of them has a mac. I was wondering if anyone know the two versions are compatible? I'd like to find out before she goes out and spend the money and find that she can't play.. Thanks in advance for any info!

edit:
I am looking for specific info on direct ip connection. Thanks!

I can't think of any reason why it wouldn't. I would have thought that the platform OS is not a issue over a IP connection, but I am no expert on this.