Can't have wireless and wired connection at same time via hub

[Modjo]

Hi all. Got a quick question from a friend of mine. He's can't connect pc and wireless (for laptop) to net at same time. His config is: cable modem-5 port hub and in that he has his pc and wireless router plugged in. He's tried all the diagnostic tools in vista, rebooting all devices, device searches etc. Any ideas? Cheers in advance