Question: what is the difference between home premium professional and ultimate windows 7?
Answer: MEMORY Windows 7 Home Premium supports a maximum of 16GB of installed RAM, whereas Professional and Ultimate can address a maximum of 192GB of RAM. [Update: To access more than 3.5GB of RAM, you need the x64 version. All editions of Windows 7 will be available in x86 and x64 versions and will ship with dual media.]