This is the script that I am using :-

RedirectOutput("hardware.txt") = 0

$wmiColl1 = GetObject("WinMgmts:root/cimv2").ExecQuery("Select * FROM Win32_ComputerSystem ")
$wmiColl2 = GetObject("WinMgmts:root/cimv2").ExecQuery("Select * FROM Win32_BIOS ")

For Each $wmiObj in $wmiColl1
? "Manufacturer: " $wmiObj.Manufacturer
? "Model: " $wmiObj.Model
? "Currently logged on user: " $wmiObj.UserName
Next

For Each $wmiObj in $wmiColl2
? "Service tag:" Trim($wmiObj.SerialNumber)
Next

Sleep 3

Is this ok ?