is the new print server integrated as part of your domain?
Couple of things to try, Have a look through the GPO settings on the server just to make sure there's no printer driver restrictions that could affect things. Also, you could try looking at the driver settings in the print server properties. If the drivers are configured using any specialised windows 7 settings, it could make it incompatible with XP.
You could also try using the admin pack from an XP workstation to connect to the print server and check the settings.

