topr8 - 4:52 pm on Mar 26, 2012 (gmt 0)
i think your site structure should reflect that the old news stories are old ...
by which i mean presumably you don't link to old stories from your home page or from the top of category pages or whatever.
therefore the search engines can tell that you don't value those pages as highly anyway. personally i cannot see any problem with 'old news' ... indeed many archive sites seem to make a living from it!