VertexDeclaration and Mesh

Hello, I'm rendering a .x file with a simple diffuse lighting shader. The model is just a sphere with a red material. If I don't set a vertex declaration, there's no vertex declaration before Mesh.DrawSubset but the declaration right after DrawSubset contains a bunch of VertexElements (Position, Normal, Color, TextureCoordinate, Tangent, Binormal). If I set the declaration to be just position and normal, it is overridden by Mesh.DrawSubset to contain the above declaration. Is Mesh.DrawSubset supposed to override any previous VertexDeclaration

I also noticed that the Mesh has 65 VertexElements in its Declaration. I exported the .x file using Maya 7 and the June 2006 SDK exporter, and MDX 1.1. Also, the .x file doesn't have any VertexFormat in it, so I can't test if it has normals.

Game Technologies: DirectX, XNA, XACT, etc.1