SELECT DISTINCT
    SYS.Netbios_Name0,
    HWSCAN.LastHWScan,
    SWSCAN.LastScanDate
FROM v_R_System SYS
LEFT join v_FullCollectionMembership fcm on fcm.ResourceID=sys.ResourceID
LEFT JOIN v_GS_LastSoftwareScan SWSCAN on SYS.ResourceID = SWSCAN.ResourceID
LEFT JOIN v_GS_WORKSTATION_STATUS HWSCAN on SYS.ResourceID = HWSCAN.ResourceID
WHERE fcm.CollectionID='YourCollectionID' and (
    DATEDIFF(DAY, HWSCAN.LastHWScan, GETDATE()) > 14 or
    DATEDIFF(DAY, SWSCAN.LastScanDate, GETDATE()) > 14 or
    HWSCAN.LastHWScan is null or
    SWSCAN.LastScanDate is null )
ORDER BY SYS.Netbios_Name0