Very quick query to find all obsolete computer objects in site system database:

Code:

SELECT
    SMS_R_SYSTEM.ResourceID,
    SMS_R_SYSTEM.ResourceType,
    SMS_R_SYSTEM.Name,
    SMS_R_SYSTEM.SMSUniqueIdentifier,
    SMS_R_SYSTEM.ResourceDomainORWorkgroup,
    SMS_R_SYSTEM.Client
FROM
    SMS_R_System
WHERE
    SMS_R_System.Obsolete = 1