My MP is hooked to my Airport Express ethernet. I'd like to hook up my XBOX 360 to APX too. Can I just hook the APX to a hub and then plug my MP and XBOX to the hub?
Is the airport express already extending an existing wireless network, and your Mac Pro is connected to it via wired ethernet? If that's the case, then it should work (edit: within the limitations of the DHCP server - extreme permits 50 connections while express has a 10 connection limit).