The SUBJECT LINE and original post is confusing then. It sounded like you wanted to convert our RasPi into a laptop/netbook. Later you mentioned you wanted a Windows computer. What do you plan on doing with the computer exactly?
Why not get a small Win10 laptop, under 12" screen size. They are small and light and thin and mostly cheap but will be under-powered, for use for light applications and net-apps (cloud apps), email, browsing, etc. A used one will be < $100, even new they are cheap. At least they are small and easy to carry, should have a reasonable battery life, etc. Again, this is way off what the original post seemed to be asking... that's why it was confusing and previous answers were all aiming to show you RasPi (which is going to necessarily be Linux-based) solutions.
The only Win you'll get on a RasPi is WinIoT core and trust me that's not going to be enough RAM or power for much of anything useful but IoT development.