As I reach the second chapter of my new HTML 5 book, I now realize, I can convert a number of sites to be fully functional with the HTML5 syntax by simply applying a small snippet of javascript in my head.

<script>
document.createElement('nav');
...
</script>

The above will ensure that my HTML5 renders correctly in IE 6,7 and 8 (already tested and works ok).
I'm using just a small minority of new tags: header,aside,nav to name just a few.

Questions:

Is this to much of a risk if the majority of my sites user base is 60% IE 6+?
Or, everybody has javascript turned on nowadays this is nothing to worry about?

Am I jumping the gun or should I start embracing these new standards?

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I'm very keen to start using HTML 5 and have a lot of clients and new job specs demanding HTML 5.
What are you thoughts on the above?

Any information/feedback much appreciated.

Barry