I've just nestled into my new Debian home and am putting on the finishing touches to suit my tastes. I'm now trying to get my long-term project to compile. Evidently, it can't find SDL or OpenGL. It produces errors like "SDL/SDL.h no such file" as so on. On a debian system, can you tell me where SDL and OpenGL are installed too and what packages are required for them? I'm not even sure i have the right packages installed. Thanks in advance.

You want the package libsdl1.2-dev and (I think) xlibmesa-gl-dev (xlibmesa-glu-dev probably, too). If you're not sure where the files are, the locate command is very handy. See man locate.

SDL and GL should both be in /usr/include like normal, under their respective folders. Ie, /usr/include/SDL/ and /usr/include/GL