I know the title is a bit of a mouth full, but just bear with me, it will make sense in the end. Windows Vista comes in both 32-bit and 64-bit flavors. The x64 versions of the operating systems are intimately connected with x64 architectures, but since such platforms can also run 32-bit versions of the Windows operating system, users should know what Windows editions they migrate from to Vista.
32-bit Windows 200 and Windows XP cannot be upgraded to 64-bit Windows Vista. Users have to perform a custom installation via the Vista media, but they can do so via an upgrade edition of Microsoft's latest operating system. The Redmond company advises users to backup all the data of the Windows 2000 or Windows XP installations via the 32-bit version of Windows Easy Transfer. Following the backup, install x64 Windows Vista and then simply restore the data form the previous version of Windows.
The process is a little more streamlined when it comes to Windows XP Professional x64. "Windows XP Professional x64 users can purchase an upgrade license for the 64-bit version of Windows Vista. However, they must perform a clean installation of the operating system. You can back up personal files and settings by using Windows Easy Transfer. Insert the upgrade version DVD of the 64-bit version of Windows Vista while the current version of Windows XP Professional x64 is running. Autorun will start the Setup program automatically, or you can manually run the Setup.exe program from the root of the DVD. Complete the steps in Windows Vista Setup," Microsoft explained, adding that the backup can be restored after the completion of the installation.
When it comes to installing x64 Vista on top of x86 Vista, things are a tad trickier. The migration cannot be done via an upgrade version of 64-bit Vista. Users will have to either buy a full license of the operating system, or revert to Windows XP and perform the installation from there. And the simplest transition of all is of course from 64-bit Vista to 64-bit Vista.
"The following list shows the 64-bit to 64-bit upgrade paths that are available: Windows Vista Home Basic to Windows Vista Premium; Windows Vista Home Basic to Windows Vista Ultimate; Windows Vista Home Premium to Windows Vista Ultimate and Windows Vista Business to Windows Vista Ultimate," Microsoft informed.