I'm having a somewhat similar connection problem. I am trying to connect my mac (which is connected to the router via ethernet) to the canon mp620, which I have set up for wireless use on the network.
I have successfully setup the printer to use the wireless network via my macbook, and can print wirelessly from the laptop to the mp620. However, I can't seem to add the printer on my mac pro, which again has a wired connection to the network. Oddly, the wireless printer shows up in the Canon IJ Network Tool, but when I open up the Canon IJ Printer Utility and select 'Network' from the printer list window, I don't see anything. Likewise, when I try to add the printer via Print/Fax prefs, and I click on 'More Printers', then select 'Canon IJ Network', nothing shows up in the list.
Does anybody know if it's even possible to connect a machine with a wired connection to a wirelessly active mp620? Perhaps I need to change some settings on my router?
Thanks,
John