i would probably go with what the other monks suggested, but here's something simple as well. I'll assume that your text file is just that, a simple text file with line returns.
to output it, try this:
in reply to How to display text in IE?
note the 'pre' tags in there. \n's at the end of lines are actually processed within those so your text file will output the way you want it to :).
print "Content-type: text/html\n\n";