I've recently done something similar. I installed cat6 wall plates in all bedrooms and public rooms wired with cat6 to a patch panel which in turn is connected to a netgear gigabit switch. My media server, broadband modem and airport base station extreme are connected to the switch to provide media, internet and wifi services.
If your looking to stream movies then I can only recommend using a wired gigabit network. I tried with wifi but it was a lagfest if I tried to stream more than one movie and/or do anything else with the server at the same time. I've tested the current setup to stream four movies at the same time to four different rooms without lag.
Hopefully it should be good enough for the kids to use when they are old enough.