There is a command called htdump from the Microsoft Reporting toolkit. Below is a code snippet I use to check if a processor is hyperthreaded.

This is useful for inventory as WMI will report 2 processors, where obviously it is not the case..

$file = "hyperthread.txt"
Shell "%comspec% /c htdump >$file"
$rc = Open (4,$file,2)
$Line = ReadLine(4)
$Hyperthread = "Processors are hyperthreading capable"
If $Line = $Hyperthread
$Hyper = 1
Else
$Hyper = 0
EndIf