From the book Tricks of Windows Game Programming Gurus by Andre LaMothe refering to windows mode programming.
The only difference is that you don't set the video mode or create a secondary back buffer. You are not allowed to page flip in windowed modes. You must either use blitter to double buffer or do it yourself, but you can't set up a complex surface chain and then call Flip().
My question is if you do want to use windows mode and hence blitter to double buffer should you go ahead and create a back buffer or use an offscreen surface instead?

Second would using the blitter and a surface to double buffer be faster then setting up your own buffer and using memcpy.

Thirdly if you set up your own buffer can you use blitter to copy from it, if so how?