Vista/XP/Printer/BT2110Router Network issues

[coolsaabdriver]

Vista computer hosts printer, XP connection issues
Xerox Phaser 8500 installed on Vista computer and we want to print to it from an XP computer.

Network facilitator is BT Voyager 2110 router. Both computers successfully access broadband through this. XP computer cannot see the printer.

I think I have networked the printer on the Vista computer

On the Vista computer I can see the Media centre from the XP computer and from the XP computer media player it can see the Vista computer. But the XP computer cannot see either the vista computer or the printer

Any suggestions as my son is driving me mad