I have run mixed networks for years, Mac, Linux, and Windows. I ALWAYS have problems with the Windows PC. I can connect the Linux and Mac together, but Windows I have to play with. I on currently running an iMac as my primary PC, and have very few problems.
One thing I didn't see mentioned here is what WIFI setup are they used using G or N. I tried G for a very time, and it wouldn't go thought walls. Nothing but trouble. I am on DSL and use my modem as the router, I have that running to a Linksys switch, and in the the living room I have Netgear router setup as a WAP. It can do confusing at first. Some people don't understand network as how to hook stuff together.
My WIFI works outside in my yard.
Homemade Offset Reverse Flow Smoker.
Soon to get a Horizon 16" Classic
Burnt up Uniflame cheapy.