This page at Dell subtitled 'Ubuntu-based Developer and Engineering systems' indicates I can buy the XPS 13 and many variants of the Precision Mobile Workstation with Ubuntu installed.  When I follow the 'Shop Now' links, however, I find that I can order only the XPS 13 with Ubuntu.  The Precision workstations only can be ordered online with Windows installed.

Should I be visiting another link, or are Precision workstations only available with Ubuntu through special order?