I also bought a new printer. Not the one I wanted but one step down from there, because I could not locate the right one locally and I didn't want to wait for it to be delivered. My understanding of the AirPort Express is that you could plug it in and it would connect wirelessly to your computer so I could plug my printer in there (with a usb cable) and it would be like having it plugged into my computer directly. I think I misunderstood. I believe it is necessary to plug the modem cable into it as well as the printer usb cable. It won't figure it out otherwise. That's what I'm figuring, which is a bit of a nuisance because the modem and linksys router (which I would then replace with the AirPort router) are in the living room and I want the printer in the office.
I've done enough damage for today, though. I think I need to rest on this. Here's what's confusing me: the other day my computer recognized my old printer. I wasn't able to use it but I think that's because it doesn't understand macs. Maybe I just need to wait until the printer shows up?