OK had this come through my email from a very trustworthy and knowledgeable individual, so i've copied and pasted it onto here, perhaps it will help
Keyword density died with the dinosaurs. If you're reading about keyword density in search engine marketing, you're reading outdated or unprofessional material. The only people who are concerned about keyword density in today's SEO world are scammers and incompetents and newcomers.
It's forgivable to be new to the search engine marketing field and be asking about keyword density, but if you've been around the search engine optimization community for a few months, you should be reasonably assured by now that the search engines don't pay attention to it.
What you want to look at in your Web copy is how natural the language appears to be. You don't want to repeat your keywords endlessly, but you do want to work them into the text of your content so that keyword density becomes irrelevant. It's not about what percentage of the text is comprised of your selected keywords, but it's about how important you show your keywords to be.
Keyword density is just one of today's Seo Myths and you can safely ignore any articles, tutorials, FAQs, and forum discussions where people talk about keyword density in a positive, favorable way and act like it is important to search engine optimization.
Search engine marketing is not about keywords. It's about creating good, useful content that is accessible and indexable.
http://www.google.com/search?hl=en&l...ankings.com%2F
