Modularizing programs into DLLs - avoiding circular dependencies.

So, in the past I've never really felt the need to modularize my program into DLLs - I had set requirements that didn't change, so i didn't feel like wasting the effort. My latest program has different requirements, and I figure that since I do so much graphics programming, it'd be in my best interest to make something that's easily reusable and upgradable without too much code copying. Being that I've never done anything like this, I'd really like to hear the best way to have so many DLLs without any corcular dependencies. I've spent all of... 30 minutes thinking of a solution, and this is what I came up with: http://img118.imageshack.us/my.php?image=engra1.jpg Am I way off base here? If I am, I'll attribute it to the fact that I just had 4 teeth pulled and am still a bit loopy from the anisthetitc.