if there is going to be some PHP in it then you need to use require or include.
file_get_contents is more efficient since it doesn't parse PHP, it just gets the text to be outputted. You don't want HTML to go through the PHP parser unless its mixed in with PHP.
p.s. i tried the host in your signature - they have been a nightmare. wouldn't ever use them again. I found them to be the opposite of reliable.