As other members said before, the sitemap will only help SE to discover your pages, in case you have a complex site, some of your content is only visible after making a search through a search form or if your menu has some crawlability problem: for instance, Javascript menus. But if what you want is improving your positioning, is relevance and links what you need. I think Google relies more on inbound links than Yahoo or MSN so you should focus on getting inbound links with the right anchor text (this is really important). In your case, your anchor text would be the same keyword you want to be positioned for: CCTV equipment. And obviously, a landing page for that link that is coherent with that same concept. Optimally, the landing page should contain this same keyword in its title, as a minimum.