Redirecting the home page to index.php, not index.html
Why use separate index files when you can use a splash screen:


  We define a splash page as being content that shows up at a specified interval, at a specified location, one time. If someone goes to a certain page for the first time, we want to make sure the splash content shows up. But if the person is coming from an internal link on the site, we don't want the splash content to show up over and over again (otherwise, the splash page would become a nuisance).


These modules implement the flash features in a Drupal site:


For D6 : https://drupal.org/project/splash
For D7 : https://drupal.org/project/splashify