Windows 7 32bit or 64bit for 16GB RAM

Absolutely. 32bit Windows cannot effectively use more than 4GB of RAM. It will mean a clean install using 64bit media though.

Windows 7 64 bit will be able to use different amounts of RAM depending on which version you get. Home Premium supports up to 16GB of RAM. Professional and Ultimate support up to 192GB of RAM. As said above, any 32 bit version of Windows 7 will only support up to 4GB of RAM.

Thanks for the quick response, by the way, is 64bit OS are better in gaming?

64-bit OS has no effect on gaming. There's very few if any games that are coded to run on 64-bit code/kernel

Best answer selected by countnebiros.