The problems I had with SDL/OpenGL and glTexImage2d have been
resolved and the programm uses SDL/OpenGL for blitting which is
indeed faster then the OPENGLBLIT I used before (woohoo! 
Joseph Carter replyed to me that the
use of glTexSubImage2d will be faster than the current
implemention with glTextImage2d. Yet I haven’t found any example
of the glTexSubImage2d function which explains me how to use it
(the nehe tutorials are great but more specified to WIN32) and
especially in conjunction with SDL.
So, could somebody provide me a link with example code how to
blit a SDL_Surface (converted to a texture) with glTexSubImage2d.
Any help is appreciated and thanks in advance!
With kind regards,
Niels Wagenaar