Newer computers often have 64-bit processors (CPUs), which allow software to access larger amounts of memory (RAM) than older 32-bit processors.
The 64-bit version of NVivo 9 can utilize this extra memory, allowing more effective use of your computer’s resources when memory demand is high. The 64-bit version of NVivo 9 requires the 64-bit version of Windows 7.
The 32-bit version of NVivo 9 can operate on a wider range of operating systems (including 64-bit Windows 7 and 64-bit Windows Vista).
If you're currently using a 32-bit version of NVivo 9, and you choose to install the 64-bit version, you must deactivate and uninstall NVivo 9 prior to installing the new version.