One inherent consumer confusion is the fact that upgrades from Windows XP to Windows Vista are limited. And when it comes down to upgrading from 32-bit Windows XP to 64-bit Windows Vista, users' options are inexistent altogether. Well let me de-mystify it for you and explain you the steps to easily Upgrade from 32-bit Windows XP to 64-bit Windows Vista.You cannot directly perform an upgrade from a 32-bit version of Windows XP to a 64-bit version of Windows Vista. However, you can use an upgrade copy of Windows Vista to perform a clean installation of a 64-bit version of Windows Vista. The simple method is that you will need to begin the installation by inserting the 64-bit Windows Vista DVD into your computer's disc drive, and then restart your computer. You must start the 64-bit Windows Vista installation from the Windows Vista 64-bit disc because Windows installation will not run on a 32-bit version of Windows.
Knowledge Base article 930891 also reveals that the 64-bit Windows Vista installation disk cannot be used to upgrade from a 32-bit Windows XP. "This behavior occurs because Windows operating system upgrades are supported only between matching operating system architectures. A 32-bit version of Windows XP does not recognize the 64-bit Windows Vista installer engine," Microsoft explains in 930891, and states that a custom installation is the only option for users that still want to use an upgrade 64-bit edition of Vista with their 32-bit Windows XP.
