Lots of members keep goats and chickens together, so I don't think keeping goats with guineas will be a problem. Maybe someone else will chime in here with other info. Welcome to our flock!
Hello and Welcome To BYC! X2 Goats and chickens usually aren't a problem, except people usually complain about the goats eating the chicken food. You might want to ask on the Guinea forum about keeping them with goats. www.backyardchickens.com/f/45/guinea-fowl
Good luck with your poultry raising adventures, and I hope you find everything you need to know. Don't forget to take a look at BYC's very useful learning center (If you haven't already)! The learning center as well as the forum should answer your questions! Glad to have you here! See you around with the flock. I'm not experienced with goats, so I don't know.