Windows Vista no longer starts after you install an earlier version of the Windows operating system in a dual-boot configuration

Have you bought a new computer with Vista preinstalled, but want to install XP don't want to wipe out Vista; you want to be able to dual boot between the two? Unfortunately, installing XP after Vista can cause Vista to be unbootable. KB article 919529 explains why and provides the solution. http://support.microsoft.com/kb/919529