Oh, you WILL get a higher framerate with OpenGL than with GDI/Graphics32. The question is do you actually need one. Typically 2D simple games like Lemmings can run at 30fps and no one notices/cares. This is "Retro Gaming" after all.

- Jeremy

PS: Graphics32 does support fading and something akin to blooms/lights. So really you could do it all in Graphics32 if you want. Best bet is to write it in a way that the render doesn't matter, build your first render in Graphics32, then build one in OpenGL, and build one in DirectX. This way you have a working (Graphics32) to compare results with.