You could consider using a projection matrix. I believe Indiepath posted some example code on how to set it in both DX and OpenGL. Search for 'projection matrix' I'm sure something will come up.
The advantage? You don't have to riddle your code with a bunch of multiplications and scaling operations. You just set your projection matrix to, let's say 800X600, then you code against that resolution but you can set the Graphics call to any resolution and it'll still render as if it was 800X600 but scaled and translated correctly.
The advantage? You don't have to riddle your code with a bunch of multiplications and scaling operations. You just set your projection matrix to, let's say 800X600, then you code against that resolution but you can set the Graphics call to any resolution and it'll still render as if it was 800X600 but scaled and translated correctly.