I found a report in NS for Primary Users. It is close to what I was looking for but this report looks to be very unreliable as it comes up with some values when queried for months after Feb.

Also I will have to select a month manually every time I run this report which I want to avoid.

Thanks,

The simplest report would be a SQL report with the following SQL:

Select
   guid, Name, User
from
  vComputer

Normally, I avoid the vComputer view like the plague, but it sorts through all the "Primary User" stuff pretty well, and comes back with one row per computer.

I'm with Jeff; in this case vComputer is the way to go.  The other option would be something like this:

SELECT acid.Name, pu.[User]
FROM Inv_AeX_AC_Identification acid
JOIN Inv_AeX_AC_Primary_User pu
ON acid._ResourceGuid = pu._ResourceGuid
WHERE pu.Month = DATENAME(month, GETDATE())
AND DATEDIFF(dd, acid.[Client Date], GETDATE()) < 90  -- only show machines which are active within 90 days
ORDER BY acid.Name ASC

Also...NS6 does not have built-in support for sending .csv files.  You can automate the report running and email it using a Notification Policy, but it won't send it as a .CSV.  If you copy the report results out of the report you can paste it into Excel and save as a CSV. 

Do you have Asset Management Suite?  If so you could use connector to do that