Hi
the first thing i would do is make sure the 3 computers are in the same workgroup. HOW.... right click my computer and select properties,,,,, under computer name note the name of the work group,,,, for example MSHOME or WORKGROUP make sure they are all the same workgroup.
if you change a workgroup name on a PC it will need to restart... do this
So the first step needs to be that when you select my computer ,,, my network places,,, then view workgroup computers that you are able to see all the pc's in the workgroup.
When you can see all three ,,,, on the computer that has the printer connected to it click on Start then Printers and faxes ,,,,, right click on the printer and select Sharing and security,,, click share and click allow network users both boxes, click ok and ok..
Hope this helps.... the main point here is you need to see all three PC's in the group.
Darren