Whenever we change the names of any files on webserver its better to make a 301 permanent redirect from the old URL to the new URL and for Linux server you can use the .htaccess to make the permanent redirect. I find a disadvantage of this as it is very much dependent on the OS of the server and if you are changing hosts then there could be a problem of old URL not being redirected and so its better to put the redirection into the code. Here are the code snippets to achive the same.
Header( "HTTP/1.1 301 Moved Permanently" );
Header( "Location: http://www.newdomain.com" );