I've just bought a second-hand Mac Pro 3GHz Quad. I fitted an Airport card (AR5BXB6), but it seems to have no range at all. My G4 Dual 1.25Ghz with an 802.11b card (sitting right next to the Mac Pro) gets three bars of wireless signal, but the Mac Pro can't even see the Linksys wireless router (WAG354G). I've tried swapping out for other Lynksys routers (I have several). No good. I can get an internet connection if I connect the Mac Pro to the router with a (long) ethernet cable, but that's not an ideal solution. I also got a good wireless connection by bringing the router right next to the Mac Pro but again, that's not the point of a wireless network. Is this low wireless range a common problem with Mac Pros?