DirectX9 or DirectX7

[TheEvilForce]

So as I posted before, there were a lot of changes in programming 2D-graphics when DirectX7 evolved to DirectX8. This means that we have to deal with on big problem. Do we want to code this project with DirectX7 (which is "old") or should we switch to DirectX9 (which is "modern").
A little summary on what happened within the area of graphics programming from DirectX7 to DirectX8/9. In DirectX7 there were Direct3D containing 3D-Graphics an DirectDraw which was necessary for 2D-Graphics. In DirectX8/9 both are put together in DirectGraphics so that DirectDraw was obsolete. As a result you have Direct3D which contains some 2D-parts (but not the way DirectDraw did).
There were changes in DirectSound too. So we should make this decision before starting with coding this game. Of course other decisions we have to make is, if we use only 2d-graphics or even 3d-graphics too (which would mean we are demanding a 3d-modeller)...