Help with frustrating network

Have fun with this,
Xp pc network can see: Vista
Vista pc network can see: Xp and Win 7
Win 7 laptop network can see: Vista

My main goal is to get the laptop to share the printer that is pluged in USB to the Xp. I can't those two to see each other in the network. I have changed the encryption, I have made sure file sharing is on, I checked other forums. I can't find this missing piece from laptop to xp. What am I doing wrong?