I've installed the Notify module to see if its a good module to allow users to be notified of new content. There doesn't seem to be a 'default' setting that will apply to new user accounts. ;(

http://drupal.org/project/notify

I finally upgraded to Drupal 4.7.1, from 4.3.0, and let me tell you it was a battle. To upgrade, you need to do every upgrade between 4.3.0 to 4.7.1, which was 4.3.0, 4.4.0, 4.5.3, 4.6.3, 4.7.1. :-D Oh Joy.