On the OP(ost), was wondering if having a BlackBerry connected to the network 24/7 is ok? You have nothing to worry about having the device connected 24/7.

Though what I would recommend is buying a dual-radio router, like the Netgear WNDR3700. You can create a separate guest network, then filter out using the MAC Addresses on your main network. Though if someone clones there network card, and figures out the password, its game over.

You will also said "What if his BB had a malware, or was infected. Stupid people can make secure stuff wide open." BB is a very secure Mobile OS. It is conseried the gold standard around the world for security in this area. Why do you think Corporations, Governments and others use them? It is because getting Malware on these devices is very hard to do. The BB also automatically scans the device for anything it considers insecure and removes at random.

As another poster stated, where did you hear there un-secure? Your PCs all hold a greater threat, then the BlackBerry can ever can make it on the network.

Also I like your taking network security very seriously.