I don`t agree with that. Like older windows-versions, it`s always the best way to install the older version first. So you install first XP, then VISTA. VISTA will regognize that there`s XP preinstalled and adds it to its bootloader. If you first install VISTA, then XP, the bootloader of VISTA is gone. That`s not really too bad - you can rebuild it by using EasyBCD. But the better way is: First older OS, then the newer. EasyBCD: http://neosmart.net/dl.php?id=1