Checked my WP Dashboard today. There's an update which fixes some 55 minor problems to WP. I have applied the new WordPress 3.0.1 update. This will be a good test now for my modifications done through the WP child theme method.
Will my changes stick or revert back to the original TwentyTen Theme?
Hooray! My theme modifications via the WordPress Child Theme remain unchanged. Yaaay!