The Xerox Phaser 6125N printer is a great piece of work, however it is not supported by default under Linux (Ubuntu 11.04 x64). 

How-ever you can use little trick to adjust the  ''Fuji-Xerox DPC525A'' CUPS ppd in such a way that is also works fine for this printer. As described over here http://ubuntuforums.org/showthread.php?t=1205253 . This steps how-ever does not alter the ppd file in such a way that it is automatically detected.

For the deb folks:
1. Download [raw-attachment:cups-xerox-phaser-6125n-1.0.0.deb]
1. $ sudo dpkg -i cups-xerox-phaser-6125n-1.0.0.deb

For the non-deb folks:
1. Download [raw-attachment:cups-xerox-phaser-6125n-1.0.0.tar.gz]
1. $ sudo tar -C / -pxzf cups-xerox-phaser-6125n-1.0.0.tar.gz