Usually this is a breeze if you know anything about networking and are careful with typing in your wireless key.

I did however think I was going a bit potty recently wirelessly networking three Macs and a PC to a BT HomeHub (BT HomeHub2 to be precise). Two of the Macs and the PC took to to the hub straight away, but the third – a G4 Cube running OS X 10.4 Tiger – kept coming up with an error after putting in the key. I tried every encryption permutation available; did it really mean WPA Personal or did it mean WPA2? Even trying to install using the BT CD-ROM, which I usually just put to one side, did not bring any joy – despite its initial enthusiasm on encountering the wireless signal from the hub. This made me realise that my fussing with the Apple networking dialog box had been in vain, because the BT installer ought to know the answer.

To the solution, then, for future reference:
Using one of the other computers that does work with the hub, navigate to the HomeHub’s own webpage (type in the router’s IP address into your browser) put in the admin password (it is on the hub itself) and find your way to its wireless settings. See where it says its signal is B/G/N and change it to B/G. And confirm.

I guess I might have been able to configure the Cube to use the N protocol. Though I doubt it having been inside this particular one I know its Airport card to be the B/G sort.

This may also help with PCs running Windows with a B/G only wireless card.