wired/wireless question

I don't think you're going to be able to do it with your current hardware.

You're going to need a router to sit between the modem and the airport base that can share the signal coming in between the PC and the airport. And you'll need a router that can output to ethernet and USB. The good news is that having a hardware router between your modem and PC will help with your PC security and they're relatively cheap.

You could return the Airport Express and get a wireless router. Or get the wireless router and keep the Express next to your stereo to use Airtunes.

Alternatively, get a wireless card for your PC so it can pick up the Express signal.

 

I think getting a wireless PCI card for the PC (assuming you have an open slot, or a USB wireless adaptor) is probably the best option. Again, if you shop around, you can get one of these for $25-30. What you really want is a 802.11g PCI card or USB adaptor that supports the WPA security standard. This should also have the advantage that you can stream iTunes wirelessly from the PC as well as the Mac. And if you want to move the PC away from the cablemodem, you're free to do so.

I just did a search, and this is one example of a cheaply available ($25 shipped) 802.11g card that should work with your airport express: http://www.compusa.com/products/pro...ven=dealm_site&cm_cat=deals1_2005&cm_pla=site