Altiris Agent Basic Inventory (no update N days) report, located in the Altiris Console at: Reports\Notification Server Infrastructure\Agent\Altiris Agent Inventory\Altiris Agent basic inventory (no update N days)
and
Computers Not Reporting Inventory in Last N Days report, located in the Altiris Console at: Reports\Asset and Inventory\Inventory\Windows\Inventory Agent\Inventory Capture\Computers Not Reporting Inventory in Last N days).
Answer
Use the Altiris Agent Basic Inventory (no update N days) report, located in the Altiris Console at: Reports\Notification Server Infrastructure\Agent\Altiris Agent Inventory\Altiris Agent basic inventory (no update N days.
DO NOT USE the Computers Not Reporting Inventory in Last N Days report, located in the Altiris Console at: Reports\Asset and Inventory\Inventory\Windows\Inventory Agent\Inventory Capture\Computers Not Reporting Inventory in Last N days). It may return inaccurate results becasue the query has a error and the reports includes some computers that have been inventoried within the parameter specified.