The printer is plugged into the Pro machine (via USB, obviously). I can print fine from that computer, however, the problem is printing from the laptop running Home Premium in the next room.
I installed the printer on the Home Premium machine by clicking add printer, then selecting Network printer. It found the printer right away and installed it. I have since updated the driver on the Home Premium machine (even though I know the problem to be in the Pro machine).
As for homegroup or workgroup, I believe we're on a homegroup. Both computers are part of the Workgroup workgroup, tho, but they do share a homegroup as well.