Hi McKay001-
Given that you don't seem to want to do anything with video, and anything with the custom texturing of 3D models in Photoshop (though that may come later - it sounds like you just want to add to the images at this point), I would suggest regular CS3.

Given that you're working to add to 3D images, the thought of working on the textures of the models themselves might be tempting, but it's still a bit more difficult to really do in actual practice (I have CS3E and it's still a bit of a headache for me).

Doing everything you laid out in your original description can easily be done in regular CS3. And you'll save a few bucks as well, so not a bad deal, really.

Hope that helps - good luck-
-Lew ;-)