Vinod: I am not saying you have to, I'm saying this is something I like to do when Asset Management is in play.
If you have a process that keeps the "Assigned To" value up to date - then why should the Discovery Tool (SCCM) update that field? Instead, have the discovery tool update a field that you can compare the Expected Assigned To (which is process managed) against the Discovery "Assigned Field" and see if it matches up and if not...why?
Also, having these fields as non-reference fields helps - if you have a local admin logging into a box or something like that that is not in the ServiceNow user table - you can at least see this data - otherwise mapping to a reference field will not show that value because it doesn't exist in the ServiceNow user table.
However, with all that said, if your current process is to map the assigned to value with what comes from discovery (SCCM) - then you are good to go. Then you can add a field to the computer table for "Last logged on user" and use the same value to map or use the top console user from SCCM.
Just some food for thought.
-Akash
