Id like to know the best way to deal with vertex arrays when doing LOD.

Basically I am rendering many seperate surfaces, and each surface is made from a 9*9 grid of vertices.

I have 4 levels of LOD that skip the approriate vertices ie

2*2
3*3
5*5
9*9

At the moment I am storing 4 seperate arrays of vertices for each surface, because I am assuming that if I pass the largest array all the time, it will transform all the vertices even if I am only indexing a few of them.

Basically my question is, are the vertex transformations defined by the contents of the vertex array, or by what is indexed?

And does locking the arrays have any affect on this?

Thanks