Powerbook G5 said:You can connect the two without Extreme, but you won't get internet since the port on the Express would be needed to connect to the modem.
Actually, it can be done. Plug a hub/switch into the Express's ethernet port. Then plug your DSL/cable modem into the hub, as well as a Mac with Internet Sharing turned on. You can then connect as many other Macs/PCs/Xboxes as you have free ports - you should even be able to 'cascade' multiple hubs together to add more free ports, if you need them.
It is possible that Apple has hard-coded iTunes to only look for Airport Expresses via Airport, but I'd be surprised. Since iTunes searches via Rendevous, it shouldn't matter whether they're connected via wired or wireless connection.