Man Obe. I have heard nothing but bad news about wired and wireless shared printers. I was looking through forums for an answer to your question, and the fixes seem to be intermittent and lack consistency. What a nightmare. For what it is worth, it isn't just Canon. They all seem to have issues.
Also the worst of it seems to be connecting differing versions of Windows. Strangely enough Windows 7 and Vista seem to be having better luck at it. This may be due to the distinct lack of W7 systems at this point.
The best solutions seem to all have the following in common.
1) Remove the drivers for all printers.
2) Clean the drivers out with any available tools (dunno if Canon has a specialized tool).
3) Clean the registry (CCLeaner should work).
4) Install the original CD drivers (if they exist for your OS).
5) Wireless PCs first. Wired Windows XP PCs second, Vista and or W7 last.
If this doesn't work, it gets chaotic fast. Download drivers, holy water, prayers, etc.
WARNING!! Many of the poor bastards started (like you) with one functioning printer and ended up with neither functioning properly when they were done. Lots of full reinstalls. So be prepared.
Hope this helps!