Don't forget that the windows firewall might be active as well.
When you installed your laptop were you connecting wirelessly also or did you take the laptop to the printer and wire them together? I'm having trouble determining what could be different between your laptop and desktop.
Can you give details of your network topology? You are wanting to access your printer through your router using wireless with both your laptop and desktop? Or is your printer connected to one of your machines (through usb) and you want to connect it with others?