I thought I had fixed my Airport problem which occured after upgrading to Leopard. However, while the network card is now working again, it cannot detect my wireless network.
Things are more complicated. My PowerMac is in my music studio, which happens to be in an old part of the house that does not have a LAN point. My only Internet source is a wireless router at the other side of the house, which I stretch out as far as possible to get the maximum signal. Usually there is no problem for my PowerMac to connect to the wireless network. However, it was only able to detect my wireless network for a brief moment in time before losing the connection totally. Subsequently it was unable to detect a network at all.
I thought maybe some hardware was damaged but after reading forum threads like this and this, I've realised many people who have upgraded to Leopard are going through the same thing. I am surprised that Apple did not do their testing properly before releasing the upgrade. Now we are all waiting with baited breath.
It is certainly an anticlimax, after marvelling at the wonders of Leopard, to discover that it impairs your Mac from doing something as basic as connecting to the Internet. Steve Jobs, are you listening? Maybe you are, and probably you're firing some manager's ass right now for overlooking this problem.
I seriously hope that Apple will release more than a 'Software Update' to fix this, as that assumes we users still have alternative ways to connect to the Internet. I cannot update my Mac this way because it does not have another Internet connection... unless someone lends me a 30-metre LAN cable which I can then wire around the house through the window to my music studio.
Long shot: Do you have bluetooth on your powermac? use gprs to dl the latest updates.
Long shot2: find your it dept to loan the cable.. normally they should have long lan cables for test.