Hi Jessica! How have you been? This glitch or conflict indeed occurred because of those two different OS's. They are not compatible with each other.
The first step here is to make sure whether your computer which is running Xp is properly connected to the 2nd printer and whether it is set to shared in the options or not.
I also wanted to ask you, can other computers see the Xp Pc and its printer? If they can see and you still get that error, you should try these steps:
Click Start button - Control Panel - Hardware and Sound - Click Printers.
Then - Add a printer.
Add Printer wizard - Add a local printer - Create a new port.
You Local Port must be selected from the list - Then Click Next
The Port Name dialog box will pop up, now type computer name/printer name, and click OK.
Complete the whole process - click Finish.
That's it, you're done!
and thank me later :)