Here is the scenario: I have a desktop computer capable of running 64bit OSs and currently has 6 GB of RAM and is running Linux. I have a 32 bit version of Windows 7 Enterprise. I know that the 32bit Windows 7 will not see more than 4GB (+/-) or RAM and that I need a 64bit version to see the other 2 GB (or 4 if I max out the system). So my question boils down to : If I were to get a Windows 7 64bit upgrade, would it be able to upgrade from the 32bit Windows 7 installation into a 64bit? Sometimes upgrades are complete wipeouts of the installed OS so I wonder if this is available for the upgrade and if so would it replace 32 for 64? Is there a way to make the 32bit version see more than 4 GB of RAM? I know Linux includes PAE in their kernel which allows seeing more than 4 GB of RAM with 32bit versions. Buying Windows 64bit and Office 2010 (and new hard drive) brings the cost close to that of a "new" system and being an older (dual-core, pre-i3, i5 or i7) machine I don't know how long it would last. This would be only for a desktop, which is centrally located and family-orientated, and the system will not be upgraded from Windows 7 (e.g. to Windows 8).