Someone

            for (int i = 2; i < vptVerticies.Count; i+= 3)
            {
                Vector3 first = vptVerticies[i].Position - vptVerticies[i-1].Position;
                Vector3 second = vptVerticies[i-1].Position - vptVerticies[i-2].Position;

                Vector3 norm = Vector3.Cross(first, second);

                norm.Normalize();

                VertexPositionNormalTexture n1 = vptVerticies[i];
                VertexPositionNormalTexture n2 = vptVerticies[i-1];
                VertexPositionNormalTexture n3 = vptVerticies[i-2];

                n1.Normal += norm;
                n2.Normal += norm;
                n3.Normal += norm;

                vptVerticies[i] = n1;
                vptVerticies[i-1] = n2;
                vptVerticies[i-2] = n3;
            }

            for (int i = 0; i < vptVerticies.Count; i ++)
            {
                VertexPositionNormalTexture vert = vptVerticies[i];

                vert.Normal.Normalize();

                vptVerticies[i] = vert;
            }