Software

  There is a report already built in to Reporting: Computers that are MIA for 60 days.  You can click into and duplicate it , and go to filters and change agent disconnection time is not within last  7 days.  Make sure to adjust the name of the report. 

you can do it with the reporting wizard

Simply click all fields you want and make it shiny.
As Filter Rule you can say "Agent Connection Time" "not within the last" "7" "days".

Or as SQL:
SELECT MACHINE.IP, MACHINE.NAME AS SYSTEM_NAME, LAST_INVENTORY, LAST_SYNC, MACHINE.ID as TOPIC_ID FROM MACHINE LEFT JOIN KBSYS.KUID_ORGANIZATION KUID_ORG ON KUID_ORG.KUID = MACHINE.KUID LEFT JOIN KBSYS.SMMP_CONNECTION SC ON MACHINE.KUID = SC.KUID AND substring(SCHEMA(),4) = KUID_ORG.ORGANIZATION_ID WHERE (((TIMESTAMP(SC.CONNECT_TIME) > NOW() OR TIMESTAMP(SC.CONNECT_TIME)
(it was created out of the query above)