Default wordpress file not index.php?

In wp 1.2 e RC1 where could I change the default file to display the wordpress loop?. I have an index page with headlines from different cats, out of the wp loop, and i want the links to the post or cat redirects to “index2.php”, or other file, not index.php (sorry for my english).It was possible in previous versions of wordpress but in the last version not.