Printer sharing between Windows 7 and Windows XP

Alright, so I've got a small network running five computers. Three of them are on Windows 7, and two are still stuck on Windows XP. On one of the Windows 7 machines, I’ve got a printer installed, and the other two Windows 7 rigs see it and share it just fine. But here's the headache: those two XP machines can't see the printer at all, even though they're properly mapped. Any ideas? Help me out here.

You could try installing the printer on machines running Windows XP as if it were a local device—say, via the LPT1 port—and then later switching the port over to a network destination. That way, the new port would look like a network path, something like \\computername\printername. I guess that might work.