The referrer information in the statistics is pretty useless. It it shows anything there at all, it doesn’t show the search terms & if you click on it, it redirects you to your own page.
If you click one of the keywords on the Search Terms tab, it should load the Visitors Log with all of the users who visited your site using those search words. Not all search engines, price comparison sites, etc, pass on the search phrase so it is impossible for this to be 100% accurate. Analytics is much more accurate but still not 100%.