Hi,
From your post I understand that you have ordered for “Dell Getting Started Computer Setup (In-Home)” for your new XPS Desktop and you are worried whether “Dell certified technician” will be able to setup you existing ATT DSL Internet.
“Dell Getting Started Computer Setup (In-Home)” includes setup of new or existing internet connection through existing service provider and confirmation of connectivity. If you have any questions about “Dell Getting Started Computer Setup (In-Home)”, you can visit this link. Please select your region from the drop-down at the top left of the screen and check for the contact options.
Hope this helps.