Lachalla,
You are right to raise this question because its not as clear cut as people are inferring. You will find that most conservative muslim arabs (mainly qataris but some other arabs too) will not bring their wives to a formal dinner, unless it is explicitly clear that men and women will be completely segregated. Other muslim arabs have a more moderate view and dinner parties with other married couples mixing together is quite acceptable, however, make sure no single men or women are invited. In both scenarios, make sure no alcohol is served at all. For non muslim colleagues, the situation is very much like anywhere else.
Lachalla,
You are right to raise this question because its not as clear cut as people are inferring. You will find that most conservative muslim arabs (mainly qataris but some other arabs too) will not bring their wives to a formal dinner, unless it is explicitly clear that men and women will be completely segregated. Other muslim arabs have a more moderate view and dinner parties with other married couples mixing together is quite acceptable, however, make sure no single men or women are invited. In both scenarios, make sure no alcohol is served at all. For non muslim colleagues, the situation is very much like anywhere else.
hope that helps
Respect
GIASI