Do you have software inventory set to inventory .dll files and to not exclude c:\windows?
If so, then the collection would look like this:
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 inner join SMS_G_System_SoftwareFile on SMS_G_System_SoftwareFile.ResourceID = SMS_R_System.ResourceId where SMS_G_System_SoftwareFile.FilePath = "C:\\Windows\\System\\" and SMS_G_System_SoftwareFile.FileName = "nlwnsck.dll"
If inventory is set correctly and the collection still doesn't populate, try this instead:
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 inner join SMS_G_System_SoftwareFile on SMS_G_System_SoftwareFile.ResourceID = SMS_R_System.ResourceId where SMS_G_System_SoftwareFile.FilePath like "%C:\\Windows\\System\\%" and SMS_G_System_SoftwareFile.FileName = "nlwnsck.dll"