Ive always been a fan of setting divs on a page then using ajax to fill in the contents of a frame depending on the users selection, so they load index up which loads maybe the header, footer and menu in, then the divContents is loaded depending on what is selected, so it never loads the entire page. This does make debugging quite fun though.
However I dont seem to see many other sites using my process, most have individual pages (with header, menu, contents and footer), others use a GET in the address (eg index.php?page=main).
Ive been reading a book on website design which points to using htaccess to redirect users to index and then read what they were trying to access and put that into the content section.
I dont really want to create pages that have to have "include header.php" and "include menu.php" on every page (seems a bit tedious), so the htaccess seems a good idea, but wonder what you experts think?