I'm not sure of the impact. But one thing Brett suggests is to link to an authority page from each page of your site for that keyword. It is part of his formula for getting top rankings. I would be interested to know the answer to this question as well...anybody else?
One piece of advice would be to have relevant anchor text in your outbounds. Another would be to check them often, so that you do not get broken links. I wrote a small piece about link maintenance in this thread: Hyperlink Maintenance (July 12, 2003) [webmasterworld.com] (post #7)