Here's one I use.
If your Ethernet works, this should too.
I have an Imac and a G4 running 10.5.4, both running with airport on a wireless network. Just bought airport card for G4 and installed with no problem, but won't connect to internet.
My Imac running 10.6.8 never asks for password, but G4 does. Used WPA password from Verizon modem/router. The G4 has no problem 'seeing' or choosing my network, but says 'connection failed' repeatedly after I enter WPA password.
Any help appreciated.