You may want to look here:
REPORTS -> Standard Reports -> Inventory -> Operating System Symmary.
A device's inventory reports the OS in this section:
COMPUTER -> OS -> Name
An OS is not an application, therefor it doesn't get tracked in SLM. The info has been in inventory however before we even came out with SLM.
NOTE - You ideally want to make sure that all your clients have got a homogeneous version of the inventory scanner (ideally the latest one), as older clients (assuming you're on 8.7 - I would be talking about things such as 8.1 or 8.5 scanners) may report things differently, causing you to have duplicate / inconsistent entries.
LANDesk EMEA Technical Lead.