MSN still accounts for keyword density, but Yahoo and Google do not anymore, they also do not read meta keywords tags either anymore.
The links are the #1 factor in top positions, but content has its place. once you get to authority status for your top level keywords you can get loads of default phrases and this can mean a lot of traffic.
To show you an example do a search in google for "click here" and you will see the adobe site in the # 1 position.
The phrase click here is not on the page, alt tags keywords title or any other place in the source code.
Here is the reason for this. How many time have you seen something similar to this on a website before.
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Links account for over 80% of top rankings.
you are wasting time with keyword density.
Now, having your keywords in the title and meta description is important, and if you can, use
tags. this will help if your words or phrases are competive.
LSI is what has done away with density standards.
hope this helps.