use the <xmp> or <pre> tags to wrap around the text of your text file that you are including.
<pre> will interpret html code, so a <br> will be translated to a line feed, href's will be linked, etc. <xmp> will show the text more verbatim.
include() is really kinda in efficient as the file is parsed as a php code, you maybe want to fopen the file, then use fpassthru in place of include()