Hey all. I need to display hi-rez (1024) video as a background. I dump the pixels to the screen with glDrawPixels. On nVidia cards this takes around 5.5ms, which is great. On ATI cards this can take up to 22ms, which is way too slow. What to do ? Is there a way to speed up glDrawPixels ? Thanks !

DrawPixels has some implementation dependent performance differences among OpenGL implementations, like color channel ordering, for example BGRA vs RGBA.
Also make sure you disabled all raster operations which are not needed, like depth test, lighting, esp. shaders.
That said, the standard answer to improve rendering perfomance of an image backdrop is to download it as a texture once and render a pixel aligned textured quad per frame.
This is expected to perform at better speeds than DrawPixels on each implementation.