Windows 10 will be officially available at the end of the month and since Windows 10 is also officially supported from ConfigMgr 2012 R2 SP1, let me quickly share you the query to create a collection containing all the Windows 10 computers.
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 = "Microsoft Windows NT Workstation 10.0 (Tablet Edition)"
In SCCM console, it should give you something like this:
BTW I really recommend trying in your lab a Windows 10 upgrade using ConfigMgr 2012 R2 SP1 and this blog post. It contains all the needed script and you just need to important the task sequence and the Windows 10 media to start already testing Windows 10 upgrade from Windows 7 or Windows 8.1!
Enjoy Windows 10, it’s awesome!