The rating on Public Service Co. of Colorado (PSCo) is based on the consolidated credit profile of integrated electric and natural gas utility holding company Xcel Energy Inc. and its vertically integrated utility subsidiaries--PSCo, Northern States Power Co. (NSP-Minnesota), Northern States Power Wisconsin (NSP-Wisconsin), and Southwestern Public Service Co. (SPS). Minneapolis, Minn.-based Xcel had $8.1 billion of debt and $105 million of preferred stock as of Dec. 31, 2007, of which PSCo had $2.5 billion of debt outstanding. Xcel, as a regulated utility holding company, serves 3.3 million electric and 1.8 million natural-gas customers in eight different states with its largest operations in Minnesota and Colorado. The rating on Xcel reflects its excellent consolidated business profile exhibited by supportive regulation,
