$Dom = @LDomain
$usr = 'guest'
 
$oUser = GetObject("WinNT://" + $Dom + "/"+ $usr + ",User" )
$RID = $oUser.Get("primaryGroupID")
$PriName = GetGroupNameFromRID($RID)
If Not @Error
	'Primary group name: ' + $PriName
EndIf
 
Function GetGroupNameFromRID($RID)
	Dim $oConnection,$oCommand,$oRootDSE
	$oConnection = CreateObject("ADODB.Connection")
	$oConnection.Open("Provider=ADsDSOObject;")
	$oCommand = CreateObject("ADODB.Command")
	$oCommand.ActiveConnection = $oConnection
	$oRootDSE = GetObject("LDAP://RootDSE")
	$oCommand.CommandText = "<LDAP://" + $oRootDSE.Get("defaultNamingContext") + ">;(objectCategory=Group);Name,primaryGroupToken;subtree"  
	$oRecSet = $oCommand.Execute
	While Not ($oRecSet.EOF Or $GetGroupNameFromRID)
	    If $oRecSet.Fields("primaryGroupToken") = $RID
	        $GetGroupNameFromRID = CStr($oRecSet.Fields("Name"))
	    EndIf
	    $oRecSet.MoveNext
	Loop
	$oConnection.Close
	Exit VarType($GetGroupNameFromRID) = 0
EndFunction