need: out true color raw bitmap from memory to window.
methods:

1. DirectDraw CopySurface
2. OpenGL DrawBitmap
3....?

what's faster/better?

I 'd recommend you opengl, it has many advantages.
i think it uses hardware acceleration on my system too, so maeby that's the reason it is faster for me. and i think it is better.
you should make a benchmark on a few systems and then you could notice differences between speeds.

MATRIX

DirectDraw is more likely to have good hardware acceleration than OpenGL - especially a lot of the older cards have poor or no GL support. GDI blit isn't too bad either.

tried OpenGl:
very good with transparences/colorisation
very bad with vcards below GeForce...

Sometimes I need out -256color- bitmap=entire screen 800x600 or 1024x768. This is really slow, more slow than from DOS vesa functions.

How it be possible speed-up?
I do:

1. get each color from bitmap
2. form true color 3xbitmap from palette table
3. out this bitmap with oGL.

very slow...

but oGl function "outBitmapIndexed (or same name)" is more slow..