After some more research I came to the conclusion that extracting Hardware infos via the Api is a never ending story... better stick to a WMI call for consistent results *sigh*... but at least I managed to "decode" the Serialnumber , at least for me it's now the same returned by WMI as the computer-info tool SIW display (which seems to use wmi too?). ; Generated by AutoIt Scriptomatic February 06, 2011 $wbemFlagReturnImmediately = 0x10 $wbemFlagForwardOnly = 0x20 $colItems = "" $strComputer