A lot of bloggers heartily recommend starting with a clean installation of Windows Vista or even purchasing (or building) a new computer to experience the full might of the operating system. That's great, in many scenarios, but in some cases you might want to upgrade your existing Windows XP or Windows 2000 installation. If your computer already meets or, better, exceeds the Windows Vista minimum system requirements and you're less interested in a shiny, clean installation than a quick and convenient upgrade, you might want to go for the in-place switcheroo.
Whether you can actually perform an in-place upgrade depends on which version of Windows you already have and which Vista you plan to get. You can only perform an in-place upgrade from certain Windows XP versions to certain Windows Vista versions; you can't upgrade any of the pre-Vista Windows operating systems (including Windows 9x/Me and Windows 2000) to Vista without performing a clean installation.
The following table shows which versions of Windows XP are capable of in-place upgrades to which versions of Windows Vista:
|Windows Vista Home Basic||Windows Vista Home Premium||Windows Vista Business||Windows Vista Ultimate|
|Windows XP Professional||No||No||Yes||Yes|
|Windows XP Home||Yes||Yes||Yes||Yes|
|Windows XP Media Center Edition||No||Yes||No||Yes|
|Windows XP Tablet PC||No||No||Yes||Yes|
Thus, you can upgrade Windows XP Home to any version of Vista; you can also upgrade any version of Windows XP to Windows Vista Ultimate. You can't upgrade XP Professional or Tablet PC to either of the Vista Home SKUs, nor can you upgrade XP Media Center to Home Basic or Business.