Looking to make life easier for everyone planning on upgrading to Windows 7, Microsoft this week published a chart detailing which OSes are eligible for an "In-Place Upgrade," and which ones require a "Custom Install."
The chart includes every OS from XP up to Windows Vista Ultimate, and even tosses in Windows Vista Starter, only found in developing nations. It appears daunting at first, but simply find the OS you're upgrading from in 32-bit or 64-bit form and match it to the version of Windows 7 you're planning to install. Owners of 32-bit Vista Home Premium, for example, can perform an In-Place Upgrade to 32-bit Windows 7 Home Premium or Ultimate. This means the settings, files, and programs will be preserved. For all other versions, including 64-bit, upgrading from 32-bit Vista Home Premium requires a Custom Install, otherwise known as a clean install.
All XP users will have to perform a clean install no matter which version of Windows 7 is selected.