Bennym,
Are you using a Linux / Apache platform ?
If yes, you can specify tons of rules via a specific file called ".htaccess". Look there :
http://wsabstract.com/howto/htaccess.shtml
You can specify which page to load when a user ask for a non-existing page (those pages which usually generate a "404 file not found" error), or - best suited in your case : which application should be launched which any file extension... Or also : which part of the site should be password protected. And so much more.
So many things which are available for free !! Enjoy.
JP