Not sure why, but the above query did not quite work. Here is my query from SCCM 2012 to list all servers that do not have the SCCM client installed:
<code>
select SMS_R_SYSTEM.ResourceID,SMS_R_SYSTEM.ResourceType,SMS_R_SYSTEM.Name,SMS_R_SYSTEM.SMSUniqueIdentifier,SMS_R_SYSTEM.ResourceDomainORWorkgroup,SMS_R_SYSTEM.Client from SMS_R_System where SMS_R_System.OperatingSystemNameandVersion like "%server%" and SMS_R_System.Client is null
</code>
-Raj W.