Pixel Description

I’m using the VC++ tutorial in the tutorial section of OpenGL.org and I’ve gone through the first few lessons and just completed the one where a “Robot” arm is created and moved via the mouse. My problem is even after I put in the Double Buffer code I still get the screen flicker. The tutorial states this is due to incompatable Pixel Description, but doesn’t say how to determine what type of pixel desc you have. Can any shed some light on the concept of a pixel describer as a whole?