Err Windows 7 has the advantage of not being incredibly insecure, which I would definitely consider a major advantage, probably the most important one for an OS

Err Windows 7 has the advantage of not being incredibly insecure, which I would definitely consider a major advantage, probably the most important one for an OS... Windows 10 is pretty resource efficient. There's even a stripped back 'long term support one' which is incredibly lightweight. Anyway, RAM is incredibly cheap now, I don't think you should be risking getting totally pwned for the sake of an investment in a few GB of ram.