Hi Chris
there are various ways you can approach this.
One is to create 2 sets of graphics (16:9 and 4:3) wich the DVD author will then use in his DVD authoring programme (scenarist) to compile 2 versions a widescreen and a full frame one (4:3). If you go down this line remember to use in your 16:9 version the 4:3 safe areas.
Start working on your graphics with the NTSC Widescreen settings, (photoshop has ready made templates) and than squeeze it down. When saving the graphics for the 4:3 version (if you used the 4:3 safe area in your 16:9 graphic)all you need to do is change the size of the canvas.
For istance on a 16:9 PAL version you would work with 1024 x 576 than squeeze to 720 x576. For the 4:3 version of the same graphic, you would first squeeze the CANVAS to 768 x 576 than the IMAGE to 720 x 576.
Also if you apply a guassian blur of about 0.3 to your final flat graphic you will help the graphic to stop shaking on the tv screen.
Or
You can do all your graphics/animations using a 16:9 setting and than the author will letterbox this in the authoring package.
Hope this helps.
Daniel