Graphics problems

Good Morning!
Still a newbie, but I got my joystick routines working fine.
Next problem: the graphics resolution and depth seem to be MUCH poorer with the SDL video than without. I am using W2K, OpenGL and an Oxygen GVX420 board in 32 bit TrueColor and stereo.
With the SDL enabled for the joystick ( which requires SDL video ) I have fewer colors in my image ( I think ) and some depth problems with a few farther images appearing in front of nearer ones. It is possible that the perceived color problem is actually the result of bleed-thru from the depth problem.
When I delete the SDL_GL_SetAtribute function calls in the initialization there is no effect. When I put them after the SDL_SetVideoMode function call, instead of before as in the manual chapter “Using OpenGL with SDL”, there still is no effect.
Is there something obvious that I’ve forgotten?